Transaminase polypeptides

ABSTRACT

The present disclosure provides engineered transaminase enzymes having improved properties as compared to a naturally occurring wild-type transaminase enzyme. Also provided are polynucleotides encoding the engineered transaminase enzymes, host cells capable of expressing the engineered transaminase enzymes, and methods of using the engineered transaminase enzymes to synthesize a variety of chiral compounds.

1. CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit under 35 U.S.C. §120 of application Ser.No. 12/684,864, filed Jan. 8, 2010, issued as U.S. Pat. No. 8,470,564 onJun. 25, 2013, and 35 U.S.C. §119(e) of application Ser. No. 61/143,401,filed Jan. 8, 2009, the contents of each of which are incorporatedherein by reference.

2. REFERENCE TO SEQUENCE LISTING, TABLE OR COMPUTER PROGRAM

The official copy of the Sequence Listing is submitted concurrently withthe specification as an ASCII formatted text file via EFS-Web, with afile name of “376247-034.txt”, a creation date of Jan. 8, 2010, and asize of 569 Kbytes. The Sequence Listing filed via EFS-Web is part ofthe specification and is incorporated in its entirety by referenceherein.

3. BACKGROUND

Aminotransferases, also known as transaminases (E.C. 2.6.1) catalyze thetransfer of an amino group, a pair of electrons, and a proton from aprimary amine of an amino donor substrate to the carbonyl group of anamino acceptor molecule. Omega-transaminases (ω-transaminases) transferamine groups which are separated from a carboxyl group by at least onemethylene insertion.

A general transaminase reaction is shown in Reaction I, below. In thisreaction, an amino acceptor (I, keto, or ketone), which is the precursorof the desired amino acid product, is reacted with an amino donor (II).The transaminase enzyme exchanges the amino group of the amino donorwith the keto group of the amino acceptor. The reaction thereforeresults in the desired chiral amine product (III) and a new aminoacceptor (keto) compound (IV), which is a by-product.

Various ω-transaminases have been isolated from microorganisms,including, but not limited to, Alcaligenes denitrificans, Bordetellabronchiseptica, Bordetella parapertussis, Brucella melitensis,Burkholderia malle, Burkholderia pseudomallei, Chromobacteriumviolaceum, Oceanicola granulosus HTCC2516, Oceanobacter sp. RED65,Oceanospirillum sp. MED92, Pseudomonas putida, Ralstonia solanacearum,Rhizobium meliloti, Rhizobium sp. (strain NGR234), Vibrio fluvialis,Bacillus thuringensis, and Klebsiella pneumoniae (Shin et al., 2001,Biosci. Biotechnol, Biochem. 65:1782-1788).

Several aminotransferase gene and enzyme sequences have also beenreported, e.g., Ralstonia solanacearum (Genbank Acc. No.YP_(—)002257813.1, GI:207739420), Burkholderia pseudomallei 1710b(Genbank Acc. No. ABA47738.1, GI:76578263), and Bordetella petrii(Genbank Acc. No. AM902716.1, GI:163258032). Two transaminases, EC2.6.1.18 and EC 2.6.1-19, have been crystallized and characterized (seeYonaha et al., 1983, Agric. Biol. Chem. 47 (10):2257-2265).

The enzyme ω-amino acid:pyruvate transaminase (ω-APT, E.C. 2.6.1.18)from Vibrio fluvialis JS17 carries out the following reaction

using pyridoxal-5′-phosphate as a cofactor. The transaminase from Vibriofluvialis has been reported to show catalytic activity toward aliphaticamines not bearing a carboxyl group.

Transaminase enzymes have potential industrial use for stereoselectivesynthesis of optically pure chiral amines and the enantiomericenrichment of chiral amines and amino acids (Shin et al., 2001, Biosci.Biotechnol. Biochem. 65:1782-1788; Iwasaki et al., 2003, Biotech. Lett.25:1843-1846; Iwasaki et al., 2004, Appl. Microb. Biotech. 69:499-505,Yun et al., 2004, Appl. Environ. Microbiol. 70:2529-2534; and Hwang etal., 2004, Enzyme Microbiol. Technol. 34:429-426). Chiral amines play animportant role in the pharmaceutical, agrochemical and chemicalindustries and are frequently used as intermediates or synthons for thepreparation of various pharmaceuticals, such as cephalosporine orpyrrolidine derivatives. Examples of the use of aminotransferases togenerate useful chemical compounds include: preparation of intermediatesand precursors of pregabalin (e.g., WO 2008/127646); the stereospecificsynthesis and enantiomeric enrichment of β-amino acids (e.g., WO2005/005633); the enantiomeric enrichment of amines (e.g., U.S. Pat. No.4,950,606; U.S. Pat. No. 5,300,437; and U.S. Pat. No. 5,169,780); andthe production of amino acids and derivatives (e.g., U.S. Pat. No.5,316,943; U.S. Pat. No. 4,518,692; U.S. Pat. No. 4,826,766; U.S. Pat.No. 6,197,558; and U.S. Pat. No. 4,600,692).

In a great number of the various applications of chiral amines, only oneparticular optically active form, either the (R) or the (S) enantiomeris physiologically active. Hence, transaminases are useful for theenantiomeric enrichment and stereoselective synthesis of chiral amines.

However, transaminases used to mediate transamination reactions can haveundesirable properties, such as instability and narrow substraterecognition profiles, thus making them undesirable for commercialapplications. Thus, there is a need for other types of transaminasesthat can be used in processes for preparing chiral amines in anoptically active form.

4. SUMMARY

The present disclosure provides transaminase polypeptides having theability to catalyze the transfer of an amino group from a donor amine toan amine acceptor molecule, polynucleotides encoding such polypeptides,and methods for using the polypeptides. Generally, transaminasepolypeptides are useful for the enantiomeric enrichment andstereoselective synthesis of chiral amines.

In one aspect, the transaminase polypeptides described herein havealtered properties as compared to a reference enzyme, such as thenaturally occurring transaminase obtained with Vibrio fluvialis (e.g.,SEQ ID NO:2) or an engineered transaminase, such as the polypeptide ofSEQ ID NO:18. Changes to enzyme properties can include, among others,improvements in enzymatic activity, stereoselectivity, sterospecificity,thermostability, solvent stability, and/or reduced substrate or productinhibition. In the embodiments herein, the altered properties are basedon engineered transaminase polypeptides having residue differences atspecific residue positions as compared to a reference sequence of anaturally occurring Vibrio fluvialis transaminase or a referenceengineered transaminase, such as the sequence of SEQ ID NO:18. In someembodiments, the residue differences are present at one or more of thefollowing residue positions: X4, X6, X9, X12, X21, X30, X31, X44, X45,X, 56, X57, X81, X82, X85, X86, X95, X112, X113, X127, X147, X153, X157,X166, X177, X181, X208, X211, X228, X233, X253, X272, X294, X297, X302,X311, X314, X316, X317, X318, X319, X320, X321, X324, X385, X391, X398,X407, X408, X409, X415, X417, X418, X420, X431, X434, X438, X444, andX446 Amino acid residues that can be present at the specified residuepositions and the associated changes to enzyme properties are providedin the detailed description.

In some embodiments, the transaminase polypeptides of the disclosure arecharacterized by increased thermostability as compared to the wild-typepolypeptide under the same reaction conditions. Thus, the polypeptidesare capable of mediating transamination reactions (e.g., reactionschemes I, II or III), as indicated by the continued formation ofproducts, at higher temperatures and for longer times than the wild-typepolypeptide. In some embodiments, the transaminase polypeptides of theinvention are improved in being able to retain activity under higherconcentrations of the donor amine, such as 2 M concentration ofisopropylamine. In some embodiments, the engineered transaminases withincreased thermostability and/or increased isopropylamine stabilitycomprises an amino acid sequence that is at least about 80%, 85%, 90%,91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more identical to thereference sequence of SEQ ID NO: 10, 16 or 18.

In some embodiments, the engineered transaminase polypeptide can haveincreased enzymatic activity as compared to the wild type transaminaseenzyme or a reference engineered transaminase for transforming thesubstrates to the products. The amount of the improvement can range frommore than 1.1 times (or fold) the enzymatic activity of thecorresponding wild-type or reference transaminase enzyme, to as much as2 times, 5 times, 10 times, 20 times, or more. In some embodiments, theengineered transaminase enzyme exhibits improved enzymatic activity thatis at least 1.1-fold, 2-fold, 3-fold, 4-fold, 5-fold, 10-fold, 25-fold,50-fold, 100-fold, 500-fold, or 1000-fold greater than that of thewild-type transaminase of SEQ ID NO:2 or a reference transaminase enzymeof SEQ ID NO:18. Improvements in enzyme activity may also haveassociated increases in stereoselectivity, stereospecificity,thermostability, solvent stability, and/or substrate binding, or reducedsubstrate and/or product inhibition.

In some embodiments, the engineered transaminases are characterized byactivity on a variety of structurally different amine acceptorsubstrates. In some embodiments, the engineered transaminases arecapable of stereoselectively converting substrates3,4-dihydronaphthalen-1(2H)-one, 1-phenylbutan-2-one,3,3-dimethylbutan-2-one, octan-2-one, 1-(4-bromophenyl)ethanone,4-phenylbutan-2-one, ethyl 3-oxobutanoate,1-(6-methoxynaphthalen-2-yl)ethanone,1-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)ethanone,1-(4-phenoxyphenyl)ethanone, (R)-4-oxotetrahydro-2H-pyran-3-yl-benzoateand/or (R)-3-(benzyloxy)dihydro-2H-pyran-4(3H)-one to the correspondingamine product at a rate that is greater than the polypeptides of SEQ IDNO:2 and/or SEQ ID NO:18.

In some embodiments, the improved transaminase polypeptide comprises anamino acid sequence corresponding to SEQ ID NO: 4, 6, 8, 10, 16, 18, 20,22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56,58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88. 90, 92,94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 122,124, 126, 128, 130, 132, 134, 136, 138, 140, 142, 144, 146, 148, 150,152, 154, 156, 158, 160, 162, 164, 166, 168, 170. 172, 174, 176, 178,180, 182, 184, 186, 188, 190, 192, 194, 196, or 198.

In some embodiments, the engineered transaminase enzymes describedherein can be obtained by mutagenizing a gene encoding anaturally-occurring wild-type transaminase enzyme that is at least 80%,81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%,95%, 96%, 97%, 98%, 99% or more identical to the amino acid sequence ofVibrio fluvialis transaminase (SEQ ID NO:2).

In another aspect, the present disclosure provides polynucleotidesencoding the engineered transaminases described herein orpolynucleotides that hybridize to such polynucleotides under highlystringent conditions. The polynucleotide can include promoters and otherregulatory elements useful for expression of the encoded engineeredtransaminase, and can utilize codons optimized for specific desiredexpression systems.

In some embodiments, the polynucleotide encoding the improvedtransaminases comprises a sequence corresponding to SEQ ID NO: 3, 5, 7,9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43,45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79,81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 101, 103, 105, 107, 109, 111,113, 115, 117, 119, 121, 123, 125, 127, 129, 131, 133, 135, 137, 139,141, 143, 145, 147, 149, 151, 153, 155, 157, 159, 161, 163, 165, 167,169, 171, 173, 175, 177, 179, 181, 183, 185, 187, 189, 191, 193, 195, or197.

In another aspect, the present disclosure provides host cells comprisingthe polynucleotides and/or expression vectors described herein. The hostcells can be Vibrio fluvialis or they may be a different organism, suchas E. coli. The host cells can be used for the expression and isolationof the engineered transaminase enzymes described herein, or,alternatively, they can be used directly for the conversion of thesubstrate to the stereoisomeric product.

In a further aspect, also provided are methods for carrying out reactionSchemes I, II or III (below) using any of the engineered transaminasesdescribed herein, which method comprises contacting or incubating theamino acceptor substrate with a transaminase polypeptide of thedisclosure in presence of an amino donor under reaction conditionssuitable for the conversion of the substrate to the amine product,thereby transforming the substrates to the product compounds. Whethercarrying out the method with whole cells, cell extracts or purifiedtransaminase enzymes, a single transaminase enzyme can be used or,alternatively, mixtures of two or more transaminase enzymes can be used.

5. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates the role of transaminases in the conversion of anamino acceptor (ketone) substrate of general formula I and an aminodonor of general formula II to the chiral amine (III) product and anamino acceptor (ketone) byproduct (IV). This reaction uses atransaminase described herein and a co-factor such aspyridoxal-5′-phosphate.

6. DETAILED DESCRIPTION 6.1 Abbreviations

The abbreviations used for the genetically encoded amino acids areconventional and are as follows:

Amino Acid Three-Letter Abbreviation One-Letter Abbreviation Alanine AlaA Arginine Arg R Asparagine Asn N Aspartate Asp D Cysteine Cys CGlutamate Glu E Glutamine Gln Q Glycine Gly G Histidine HIS H IsoleucineIle I Leucine Leu L Lysine Lys K Methionine Met M Phenylalanine Phe FProline Pro P Serine Ser S Threonine Thr T Tryptophan Trp W Tyrosine TyrY Valine Val V

When the three-letter abbreviations are used, unless specificallypreceded by an “L” or a “D” or clear from the context in which theabbreviation is used, the amino acid may be in either the L- orD-configuration about α-carbon (C_(α)). For example, whereas “Ala”designates alanine without specifying the configuration about theα-carbon, “D-Ala” and “L-Ala” designate D-alanine and L-alanine,respectively. When the one-letter abbreviations are used, upper caseletters designate amino acids in the L-configuration about the α-carbonand lower case letters designate amino acids in the D-configurationabout the α-carbon. For example, “A” designates L-alanine and “a”designates D-alanine. When polypeptide sequences are presented as astring of one-letter or three-letter abbreviations (or mixturesthereof), the sequences are presented in the amino (N) to carboxy (C)direction in accordance with common convention.

The abbreviations used for the genetically encoding nucleosides areconventional and are as follows: adenosine (A); guanosine (G); cytidine(C); thymidine (T); and uridine (U). Unless specifically delineated, theabbreviated nucleotides may be either ribonucleosides or2′-deoxyribonucleosides. The nucleosides may be specified as beingeither ribonucleosides or 2′-deoxyribonucleosides on an individual basisor on an aggregate basis. When nucleic acid sequences are presented as astring of one-letter abbreviations, the sequences are presented in the5′ to 3′ direction in accordance with common convention, and thephosphates are not indicated.

6.2 Definitions

As used herein, the following terms are intended to have the followingmeanings.

“Protein”, “polypeptide,” and “peptide” are used interchangeably hereinto denote a polymer of at least two amino acids covalently linked by anamide bond, regardless of length or post-translational modification(e.g., glycosylation, phosphorylation, lipidation, myristilation,ubiquitination, etc.). Included within this definition are D- andL-amino acids, and mixtures of D- and L-amino acids.

“Aminotransferase” and “transaminase” are used interchangeably herein torefer to a polypeptide having an enzymatic capability of transferring anamino group (NH₂), a pair of electrons, and a proton from a primaryamine to a carbonyl group (C═O) of an acceptor molecule. Morespecifically, the transaminase polypeptides are capable ofstereoselectively catalyzing the process of Scheme 1 (below).Transaminases as used herein include naturally occurring (wild type)transaminase as well as non-naturally occurring engineered polypeptidesgenerated by human manipulation.

“Amino acceptor” and “amine acceptor”, “keto substrate”, “keto” and“ketone” are used interchangeably herein to refer to a carbonyl (keto,or ketone) compound which accepts an amino group from a donor amineAmino acceptors are molecules of general Formula I,

in which each of R¹, R², when taken independently, is an alkyl, analkylaryl group, or aryl group which is unsubstituted or substitutedwith one or more enzymatically acceptable groups. R¹ may be the same ordifferent from R² in structure or chirality. R¹ and R², taken together,may form a ring that is unsubstituted, substituted, or fused to otherrings Amino acceptors include keto carboxylic acids and alkanones(ketones). Typical keto carboxylic acids are α-keto carboxylic acidssuch as glyoxalic acid, pyruvic acid, oxaloacetic acid, and the like, aswell as salts of these acids Amino acceptors also include substanceswhich are converted to an amino acceptor by other enzymes or whole cellprocesses, such as fumaric acid (which can be converted to oxaloaceticacid), glucose (which can be converted to pyruvate), lactate, maleicacid, and others Amino acceptors that can be used include, by way ofexample and not limitation, 3,4-dihydronaphthalen-1(2H)-one,1-phenylbutan-2-one, 3,3-dimethylbutan-2-one, octan-2-one, ethyl3-oxobutanoate, 4-phenylbutan-2-one, 1-(4-bromophenyl)ethanone,2-methyl-cyclohexamone, 7-methoxy-2-tetralone, 1-hydroxybutan-2-one,pyruvic acid, acetophenone, 2-methoxy-5-fluoroacetophenone, levulinicacid, 1-phenylpropan-1-one, 1-(4-bromophenyl)propan-1-one,1-(4-nitrophenyl)propan-1-one, 1-phenylpropan-2-one,2-oxo-3-methylbutanoic acid,1-(3-trifluoromethylphenyl)propan-1-one,hydroxypropanone,methoxyoxypropanone, 1-phenylbutan-1-one,1-(2,5-dimethoxy-4-methylphenyl)butan-2-one,1-(4-hydroxyphenyl)butan-3-one, 2-acetylnaphthalene, phenylpyruvic acid,2-ketoglutaric acid, and 2-ketosuccinic acid, including both (R) and (S)single isomers where possible.

“Amino donor” refers to an amino compound which donates an amino groupto the amino acceptor, thereby becoming a carbonyl species Amino donorsare molecules of general Formula II,

in which each of R³, R⁴, when taken independently, is an alkyl, analkylaryl group, or aryl group which is unsubstituted or substitutedwith one or more enzymatically non-inhibiting groups. R³ can be the sameor different from R⁴ in structure or chirality. R³ and R⁴, takentogether, may form a ring that is unsubstituted, substituted, or fusedto other rings. Typical amino donors that can be used with the inventioninclude chiral and achiral amino acids, and chiral and achiral amines.Amino donors that can be used with the invention include, by way ofexample and not limitation, isopropylamine (also termed 2-aminopropane),α-phenethylamine (also termed 1-phenylethanamine), and its enantiomers(S)-1-phenylethanamine and (R)-1-phenylethanamine,2-amino-4-phenylbutane, glycine, L-glutamic acid, L-glutamate,monosodium glutamate, L-alanine, D-alanine, D,L-alanine, L-asparticacid, L-lysine, L-ornithine, f3-alanine, taurine, n-octylamine,cyclohexylamine, 1,4-butanediamine, 1,6-hexanediamine, 6-aminohexanoicacid, 4-aminobutyric acid, tyramine, and benzyl amine, 2-aminobutane,2-amino-1-butanol, 1-amino-1-phenylethane,1-amino-1-(2-methoxy-5-fluorophenyl)ethane, 1-amino-1-phenylpropane,1-amino-1-(4-hydroxyphenyl)propane, 1-amino-1-(4-bromophenyl)propane,1-amino-1-(4-nitrophenyl)propane, 1-phenyl-2-aminopropane,1-(3-trifluoromethylphenyl)-2-aminopropane, 2-aminopropanol,1-amino-1-phenylbutane, 1-phenyl-2-aminobutane,1-(2,5-dimethoxy-4-methylphenyl)-2-aminobutane, 1-phenyl-3-aminobutane,1-(4-hydroxyphenyl)-3-aminobutane, 1-amino-2-methylcyclopentane,1-amino-3-methylcyclopentane, 1-amino-2-methylcyclohexane,1-amino-1-(2-naphthyl)ethane, 3-methylcyclopentylamine,2-methylcyclopentylamine, 2-ethylcyclopentylamine,2-methylcyclohexylamine, 3-methylcyclohexylamine, 1-aminotetralin,2-aminotetralin, 2-amino-5-methoxytetralin, and 1-aminoindan, includingboth (R) and (S) single isomers where possible and including allpossible salts of the amines.

“Chiral amine” refers to amines of general formula R¹—CH(NH₂)—R² and isemployed herein in its broadest sense, including a wide variety ofaliphatic and alicyclic compounds of different, and mixed, functionaltypes, characterized by the presence of a primary amino group bound to asecondary carbon atom which, in addition to a hydrogen atom, carrieseither (i) a divalent group forming a chiral cyclic structure, or (ii)two substituents (other than hydrogen) differing from each other instructure or chirality. Divalent groups forming a chiral cyclicstructure include, for example, 2-methylbutane-1,4-diyl,pentane-1,4-diyl,hexane-1,4-diyl, hexane-1,5-diyl,2-methylpentane-1,5-diyl. The two different substituents on thesecondary carbon atom (R¹ and R² above) also can vary widely and includealkyl, aralkyl, aryl, halo, hydroxy, lower alkyl, lower alkoxy, loweralkylthio, cycloalkyl, carboxy, cabalkoxy, carbamoyl, mono- anddi-(lower alkyl) substituted carbamoyl, trifiuoromethyl, phenyl, nitro,amino, mono- and di-(lower alkyl) substituted amino, alkylsulfonyl,arylsulfonyl, alkylcarboxamido, arylcarboxamido, etc., as well as alkyl,aralkyl, or aryl substituted by the foregoing.

“Pyridoxal-phosphate”, “PLP”, “pyridoxal-5′-phosphate”, “PYP”, and “P5P”are used interchangeably herein to refer to the compound that acts as acoenzyme in transaminase reactions. In some embodiments, pyridoxalphosphate is defined by the structure1-(4′-formyl-3′-hydroxy-2′-methyl-5′-pyridyl)methoxyphosphonic acid, CASnumber [54-47-7], Pyridoxal-5′-phosphate can be produced in vivo byphosphorylation and oxidation of pyridoxol (also known as Vitamin B₆).In transamination reactions using transaminase enzymes, the amine groupof the amino donor is transferred to the coenzyme to produce a ketobyproduct, while pyridoxal-5′-phosphate is converted to pyridoxaminephosphate. Pyridoxal-5′-phosphate is regenerated by reaction with adifferent keto compound (the amino acceptor). The transfer of the aminegroup from pyridoxamine phosphate to the amino acceptor produces achiral amine and regenerates the coenzyme. In some embodiments, thepyridoxal-5′-phosphate can be replaced by other members of the vitaminB₆ family, including pyridoxine (PN), pyridoxal (PL), pyridoxamine (PM),and their phosphorylated counterparts; pyridoxine phosphate (PNP), andpyridoxamine phosphate (PMP).

“Coding sequence” refers to that portion of a nucleic acid (e.g., agene) that encodes an amino acid sequence of a protein.

“Naturally-occurring” or “wild-type” refers to the form found in nature.For example, a naturally occurring or wild-type polypeptide orpolynucleotide sequence is a sequence present in an organism that can beisolated from a source in nature and which has not been intentionallymodified by human manipulation.

“Recombinant” or “engineered” or “non-naturally occurring” when usedwith reference to, e.g., a cell, nucleic acid, or polypeptide, refers toa material, or a material corresponding to the natural or native form ofthe material, that has been modified in a manner that would nototherwise exist in nature, or is identical thereto but produced orderived from synthetic materials and/or by manipulation usingrecombinant techniques. Non-limiting examples include, among others,recombinant cells expressing genes that are not found within the native(non-recombinant) form of the cell or express native genes that areotherwise expressed at a different level.

“Percentage of sequence identity” and “percentage homology” are usedinterchangeably herein to refer to comparisons among polynucleotides andpolypeptides, and are determined by comparing two optimally alignedsequences over a comparison window, wherein the portion of thepolynucleotide or polypeptide sequence in the comparison window maycomprise additions or deletions (i.e., gaps) as compared to thereference sequence for optimal alignment of the two sequences. Thepercentage may be calculated by determining the number of positions atwhich the identical nucleic acid base or amino acid residue occurs inboth sequences to yield the number of matched positions, dividing thenumber of matched positions by the total number of positions in thewindow of comparison and multiplying the result by 100 to yield thepercentage of sequence identity. Alternatively, the percentage may becalculated by determining the number of positions at which either theidentical nucleic acid base or amino acid residue occurs in bothsequences or a nucleic acid base or amino acid residue is aligned with agap to yield the number of matched positions, dividing the number ofmatched positions by the total number of positions in the window ofcomparison and multiplying the result by 100 to yield the percentage ofsequence identity. Those of skill in the art appreciate that there aremany established algorithms available to align two sequences. Optimalalignment of sequences for comparison can be conducted, e.g., by thelocal homology algorithm of Smith and Waterman, 1981, Adv. Appl. Math.2:482, by the homology alignment algorithm of Needleman and Wunsch,1970, J. Mol. Biol. 48:443, by the search for similarity method ofPearson and Lipman, 1988, Proc. Natl. Acad. Sci. USA 85:2444, bycomputerized implementations of these algorithms (GAP, BESTFIT, FASTA,and TFASTA in the GCG Wisconsin Software Package), or by visualinspection (see generally, Current Protocols in Molecular Biology, F. M.Ausubel et al., eds., Current Protocols, a joint venture between GreenePublishing Associates, Inc. and John Wiley & Sons, Inc., (1995Supplement) (Ausubel)). Examples of algorithms that are suitable fordetermining percent sequence identity and sequence similarity are theBLAST and BLAST 2.0 algorithms, which are described in Altschul et al.,1990, J. Mol. Biol. 215: 403-410 and Altschul et al., 1977, NucleicAcids Res. 3389-3402, respectively. Software for performing BLASTanalyses is publicly available through the National Center forBiotechnology Information website. This algorithm involves firstidentifying high scoring sequence pairs (HSPs) by identifying shortwords of length W in the query sequence, which either match or satisfysome positive-valued threshold score T when aligned with a word of thesame length in a database sequence. T is referred to as, theneighborhood word score threshold (Altschul et al, supra). These initialneighborhood word hits act as seeds for initiating searches to findlonger HSPs containing them. The word hits are then extended in bothdirections along each sequence for as far as the cumulative alignmentscore can be increased. Cumulative scores are calculated using, fornucleotide sequences, the parameters M (reward score for a pair ofmatching residues; always >0) and N (penalty score for mismatchingresidues; always <0). For amino acid sequences, a scoring matrix is usedto calculate the cumulative score. Extension of the word hits in eachdirection are halted when: the cumulative alignment score falls off bythe quantity X from its maximum achieved value; the cumulative scoregoes to zero or below, due to the accumulation of one or morenegative-scoring residue alignments; or the end of either sequence isreached. The BLAST algorithm parameters W, T, and X determine thesensitivity and speed of the alignment. The BLASTN program (fornucleotide sequences) uses as defaults a wordlength (W) of 11, anexpectation (E) of 10, M=5, N=−4, and a comparison of both strands. Foramino acid sequences, the BLASTP program uses as defaults a wordlength(W) of 3, an expectation (E) of 10, and the BLOSUM62 scoring matrix (seeHenikoff and Henikoff, 1989, Proc Natl Acad Sci USA 89:10915). Exemplarydetermination of sequence alignment and % sequence identity can employthe BESTFIT or GAP programs in the GCG Wisconsin Software package(Accelrys, Madison Wis.), using default parameters provided.

“Reference sequence” refers to a defined sequence used as a basis for asequence comparison. A reference sequence may be a subset of a largersequence, for example, a segment of a full-length gene or polypeptidesequence. Generally, a reference sequence is at least 20 nucleotide oramino acid residues in length, at least 25 residues in length, at least50 residues in length, or the full length of the nucleic acid orpolypeptide. Since two polynucleotides or polypeptides may each (1)comprise a sequence (i.e., a portion of the complete sequence) that issimilar between the two sequences, and (2) may further comprise asequence that is divergent between the two sequences, sequencecomparisons between two (or more) polynucleotides or polypeptide aretypically performed by comparing sequences of the two polynucleotides orpolypeptides over a “comparison window” to identify and compare localregions of sequence similarity.

In some embodiments, a “reference sequence” can be based on a primaryamino acid sequence, where the reference sequence is a sequence that canhave one or more changes in the primary sequence. For instance, a“reference sequence based on SEQ ID NO:2 having at the residuecorresponding to X85 an alanine or valine” refers to a referencesequence in which the corresponding residue at X85 in SEQ ID NO:2, whichis a phenylalanine, has been changed to an alanine or valine.

“Comparison window” refers to a conceptual segment of at least about 20contiguous nucleotide positions or amino acids residues wherein asequence may be compared to a reference sequence of at least 20contiguous nucleotides or amino acids and wherein the portion of thesequence in the comparison window may comprise additions or deletions(i.e., gaps) of 20 percent or less as compared to the reference sequence(which does not comprise additions or deletions) for optimal alignmentof the two sequences. The comparison window can be longer than 20contiguous residues, and includes, optionally 30, 40, 50, 100, or longerwindows.

“Substantial identity” refers to a polynucleotide or polypeptidesequence that has at least 80 percent sequence identity, at least 85percent identity and 89 to 95 percent sequence identity, more usually atleast 99 percent sequence identity as compared to a reference sequenceover a comparison window of at least 20 residue positions, frequentlyover a window of at least 30-50 residues, wherein the percentage ofsequence identity is calculated by comparing the reference sequence to asequence that includes deletions or additions which total 20 percent orless of the reference sequence over the window of comparison. Inspecific embodiments applied to polypeptides, the term “substantialidentity” means that two polypeptide sequences, when optimally aligned,such as by the programs GAP or BESTFIT using default gap weights, shareat least 80 percent sequence identity, preferably at least 89 percentsequence identity, at least 95 percent sequence identity or more (e.g.,99 percent sequence identity). Preferably, residue positions which arenot identical differ by conservative amino acid substitutions.

“Corresponding to”, “reference to” or “relative to” when used in thecontext of the numbering of a given amino acid or polynucleotidesequence refers to the numbering of the residues of a specifiedreference sequence when the given amino acid or polynucleotide sequenceis compared to the reference sequence. In other words, the residuenumber or residue position of a given polymer is designated with respectto the reference sequence rather than by the actual numerical positionof the residue within the given amino acid or polynucleotide sequence.For example, a given amino acid sequence, such as that of an engineeredtransaminase, can be aligned to a reference sequence by introducing gapsto optimize residue matches between the two sequences. In these cases,although the gaps are present, the numbering of the residue in the givenamino acid or polynucleotide sequence is made with respect to thereference sequence to which it has been aligned.

“Stereoselectivity” refers to the preferential formation in a chemicalor enzymatic reaction of one stereoisomer over another.Stereoselectivity can be partial, where the formation of onestereoisomer is favored over the other, or it may be complete where onlyone stereoisomer is formed. When the stereoisomers are enantiomers, thestereoselectivity is referred to as enantioselectivity, the fraction(typically reported as a percentage) of one enantiomer in the sum ofboth. It is commonly alternatively reported in the art (typically as apercentage) as the enantiomeric excess (e.e.) calculated therefromaccording to the formula [major enantiomer−minor enantiomer]/[majorenantiomer+minor enantiomer]. Where the stereoisomers arediastereoisomers, the stereoselectivity is referred to asdiastereoselectivity, the fraction (typically reported as a percentage)of one diastereomer in a mixture of two diasteromers, commonlyalternatively reported as the diastereomeric excess (d.e.). Enantiomericexcess and diastereomeric excess are types of stereomeric excess.

“Highly stereoselective” refers to a transaminase polypeptide that iscapable of converting the substrate to the corresponding chiral amineproduct with at least about 85% stereomeric excess.

“Stereospecificity” refers to the preferential conversion in a chemicalor enzymatic reaction of one stereoisomer over another.Stereospecificity can be partial, where the conversion of onestereoisomer is favored over the other, or it may be complete where onlyone stereoisomer is converted.

“Chemoselectivity” refers to the preferential formation in a chemical orenzymatic reaction of one product over another.

“Improved enzyme property” refers to a transaminase polypeptide thatexhibits an improvement in any enzyme property as compared to areference transaminase. For the engineered transaminase polypeptidesdescribed herein, the comparison is generally made to the wild-typetransaminase enzyme, although in some embodiments, the referencetransaminase can be another improved engineered transaminase. Enzymeproperties for which improvement is desirable include, but are notlimited to, enzymatic activity (which can be expressed in terms ofpercent conversion of the substrate), thermo stability, solventstability, pH activity profile, cofactor requirements, refractoriness toinhibitors (e.g., substrate or product inhibition), stereospecificity,and stereoselectivity (including enantioselectivity).

“Increased enzymatic activity” refers to an improved property of theengineered transaminase polypeptides, which can be represented by anincrease in specific activity (e.g., product produced/time/weightprotein) or an increase in percent conversion of the substrate to theproduct (e.g., percent conversion of starting amount of substrate toproduct in a specified time period using a specified amount oftransaminase) as compared to the reference transaminase enzyme.Exemplary methods to determine enzyme activity are provided in theExamples. Any property relating to enzyme activity may be affected,including the classical enzyme properties of K_(m), V_(max) or k_(cat),changes of which can lead to increased enzymatic activity. Improvementsin enzyme activity can be from about 1.1 times the enzymatic activity ofthe corresponding wild-type transaminase enzyme, to as much as 2 times,5 times, 10 times, 20 times, 25 times, 50 times, 75 times, 100 times, ormore enzymatic activity than the naturally occurring transaminase oranother engineered transaminase from which the transaminase polypeptideswere derived. In specific embodiments, the engineered transaminaseenzyme exhibits improved enzymatic activity in the range of 1.5 to 50times, 1.5 to 100 times greater than that of the parent transaminaseenzyme. It is understood by the skilled artisan that the activity of anyenzyme is diffusion limited such that the catalytic turnover rate cannotexceed the diffusion rate of the substrate, including any requiredcofactors. The theoretical maximum of the diffusion limit, ork_(cat)/K_(m), is generally about 10⁸ to 10⁹ (M⁻¹ s⁻¹). Hence, anyimprovements in the enzyme activity of the transaminase will have anupper limit related to the diffusion rate of the substrates acted on bythe transaminase enzyme. Transaminase activity can be measured by anyone of standard assays, such as by monitoring changes inspectrophotometric properties of reactants or products. In someembodiments, the amount of products produced can be measured byHigh-Performance Liquid Chromatography (HPLC) separation combined withUV absorbance or fluorescent detection following o-phthaldialdehyde(OPA) derivitization. Comparisons of enzyme activities are made using adefined preparation of enzyme, a defined assay under a set condition,and one or more defined substrates, as further described in detailherein. Generally, when lysates are compared, the numbers of cells andthe amount of protein assayed are determined as well as use of identicalexpression systems and identical host cells to minimize variations inamount of enzyme produced by the host cells and present in the lysates.

“Conversion” refers to the enzymatic conversion of the substrate(s) tothe corresponding product(s). “Percent conversion” refers to the percentof the substrate that is converted to the product within a period oftime under specified conditions. Thus, the “enzymatic activity” or“activity” of a transaminase polypeptide can be expressed as “percentconversion” of the substrate to the product.

“Thermostable” refers to a transaminase polypeptide that maintainssimilar activity (more than 60% to 80% for example) after exposure toelevated temperatures (e.g., 40-80° C.) for a period of time (e.g.,0.5-24 hrs) compared to the wild-type enzyme.

“Solvent stable” refers to a transaminase polypeptide that maintainssimilar activity (more than e.g., 60% to 80%) after exposure to varyingconcentrations (e.g., 5-99%) of solvent (ethanol, isopropyl alcohol,dimethylsulfoxide (DMSO), tetrahydrofuran, 2-methyltetrahydrofuran,acetone, toluene, butyl acetate, methyl tert-butyl ether, etc.) for aperiod of time (e.g., 0.5-24 hrs) compared to the wild-type enzyme.

“pH stable” refers to a transaminase polypeptide that maintains similaractivity (more than e.g., 60% to 80%) after exposure to high or low pH(e.g. 4.5-6 or 8 to 12) for a period of time (e.g. 0.5-24 hrs) comparedto the untreated enzyme.

“Thermo- and solvent stable” refers to a transaminase polypeptide thatis both thermostable and solvent stable.

“Derived from” as used herein in the context of engineered transaminaseenzymes, identifies the originating transaminase enzyme, and/or the geneencoding such transaminase enzyme, upon which the engineering was based.For example, the engineered transaminase enzyme of SEQ ID NO:18 wasobtained by artificially evolving, over multiple generations the geneencoding the Vibrio fluvialis transaminase enzyme of SEQ ID NO:2. Thus,this engineered transaminase enzyme is “derived from” the wild-typetransaminase of SEQ ID NO:2.

“Hydrophilic Amino Acid or Residue” refers to an amino acid or residuehaving a side chain exhibiting a hydrophobicity of less than zeroaccording to the normalized consensus hydrophobicity scale of Eisenberget al., 1984, J. Mol. Biol. 179:125-142. Genetically encoded hydrophilicamino acids include L-Thr (T), L-Ser (S), L-His (H), L-Glu (E), L-Asn(N), L-Gln (Q), L-Asp (D), L-Lys (K) and L-Arg (R).

“Acidic Amino Acid or Residue” refers to a hydrophilic amino acid orresidue having a side chain exhibiting a pK value of less than about 6when the amino acid is included in a peptide or polypeptide. Acidicamino acids typically have negatively charged side chains atphysiological pH due to loss of a hydrogen ion. Genetically encodedacidic amino acids include L-Glu (E) and L-Asp (D).

“Basic Amino Acid or Residue” refers to a hydrophilic amino acid orresidue having a side chain exhibiting a pK value of greater than about6 when the amino acid is included in a peptide or polypeptide. Basicamino acids typically have positively charged side chains atphysiological pH due to association with hydronium ion. Geneticallyencoded basic amino acids include L-Arg (R) and L-Lys (K).

“Polar Amino Acid or Residue” refers to a hydrophilic amino acid orresidue having a side chain that is uncharged at physiological pH, butwhich has at least one bond in which the pair of electrons shared incommon by two atoms is held more closely by one of the atoms.Genetically encoded polar amino acids include L-Asn (N), L-Gln (Q),L-Ser (S) and L-Thr (T).

“Hydrophobic Amino Acid or Residue” refers to an amino acid or residuehaving a side chain exhibiting a hydrophobicity of greater than zeroaccording to the normalized consensus hydrophobicity scale of Eisenberget al., 1984, J. Mol. Biol. 179:125-142. Genetically encoded hydrophobicamino acids include L-Pro (P), L-Ile (I), L-Phe (F), L-Val (V), L-Leu(L), L-Trp (W), L-Met (M), L-Ala (A) and L-Tyr (Y).

“Aromatic Amino Acid or Residue” refers to a hydrophilic or hydrophobicamino acid or residue having a side chain that includes at least onearomatic or heteroaromatic ring. Genetically encoded aromatic aminoacids include L-Phe (F), L-Tyr (Y) and L-Trp (W). Although owing to thepKa of its heteroaromatic nitrogen atom L-His (H) it is sometimesclassified as a basic residue, or as an aromatic residue as its sidechain includes a heteroaromatic ring, herein histidine is classified asa hydrophilic residue or as a “constrained residue” (see below).

“Constrained Amino Acid or Residue” refers to an amino acid or residuethat has a constrained geometry. Herein, constrained residues includeL-pro (P) and L-his (H). Histidine has a constrained geometry because ithas a relatively small imidazole ring. Proline has a constrainedgeometry because it also has a five membered ring.

“Non-polar Amino Acid or Residue” refers to a hydrophobic amino acid orresidue having a side chain that is uncharged at physiological pH andwhich has bonds in which the pair of electrons shared in common by twoatoms is generally held equally by each of the two atoms (i.e., the sidechain is not polar). Genetically encoded non-polar amino acids includeL-Gly (G), L-Leu (L), L-Val (V), L-Ile (I), L-Met (M) and L-Ala (A).

“Aliphatic Amino Acid or Residue” refers to a hydrophobic amino acid orresidue having an aliphatic hydrocarbon side chain. Genetically encodedaliphatic amino acids include L-Ala (A), L-Val (V), L-Leu (L) and L-Ile(I).

“Cysteine” represented by L-Cys (C) is unusual in that it can formdisulfide bridges with other L-Cys (C) amino acids or other sulfanyl- orsulfhydryl-containing amino acids. The “cysteine-like residues” includecysteine and other amino acids that contain sulfhydryl moieties that areavailable for formation of disulfide bridges. The ability of L-Cys (C)(and other amino acids with —SH containing side chains) to exist in apeptide in either the reduced free —SH or oxidized disulfide-bridgedform affects whether L-Cys (C) contributes net hydrophobic orhydrophilic character to a peptide. While L-Cys (C) exhibits ahydrophobicity of 0.29 according to the normalized consensus scale ofEisenberg (Eisenberg et al., 1984, supra), it is to be understood thatfor purposes of the present disclosure L-Cys (C) is categorized into itsown unique group.

“Small Amino Acid or Residue” refers to an amino acid or residue havinga side chain that is composed of a total three or fewer carbon and/orheteroatoms (excluding the α-carbon and hydrogens). The small aminoacids or residues may be further categorized as aliphatic, non-polar,polar or acidic small amino acids or residues, in accordance with theabove definitions. Genetically-encoded small amino acids include L-Ala(A), L-Val (V), L-Cys (C), L-Asn (N), L-Ser (S), L-Thr (T) and L-Asp(D).

“Hydroxyl-containing Amino Acid or Residue” refers to an amino acidcontaining a hydroxyl (—OH) moiety. Genetically-encodedhydroxyl-containing amino acids include L-Ser (S) L-Thr (T) and L-Tyr(Y).

“Amino acid difference” or “residue difference” refers to a change inthe residue at a specified position of a polypeptide sequence whencompared to a reference sequence. For example, a residue difference atposition X9, where the reference sequence has an alanine, refers to achange of the residue at position X9 to any residue other than alanine.As disclosed herein, an enzyme can include one or more residuedifferences relative to a reference sequence, where multiple residuedifferences typically are indicated by a list of the specified positionswhere changes are made relative to the reference sequence.

“Conservative” amino acid substitutions or mutations refer to theinterchangeability of residues having similar side chains, and thustypically involves substitution of the amino acid in the polypeptidewith amino acids within the same or similar defined class of aminoacids. However, in some embodiments, conservative mutations as usedherein do not include substitutions from a hydrophilic to hydrophilic,hydrophobic to hydrophobic, hydroxyl-containing to hydroxyl-containing,or small to small residue, if the conservative mutation can instead be asubstitution from an aliphatic to an aliphatic, non-polar to non-polar,polar to polar, acidic to acidic, basic to basic, aromatic to aromatic,or constrained to constrained residue. Further, as used herein, A, V, L,or I can be conservatively mutated to either another aliphatic residueor to another non-polar residue. The table below shows exemplaryconservative substitutions.

Residue Possible Conservative Mutations A, L, V, I Other aliphatic (A,L, V, I) Other non-polar (A, L, V, I, G, M) G, M Other non-polar (A, L,V, I, G, M) D, E Other acidic (D, E) K, R Other basic (K, R) P, H Otherconstrained (P, H) N, Q, S, T Other polar Y, W, F Other aromatic (Y, W,F) C None

“Non-conservative substitution” refers to substitution or mutation of anamino acid in the polypeptide with an amino acid with significantlydiffering side chain properties. Non-conservative substitutions may useamino acids between, rather than within, the defined groups listedabove. In one embodiment, a non-conservative mutation affects (a) thestructure of the peptide backbone in the area of the substitution (e.g.,proline for glycine) (b) the charge or hydrophobicity, or (c) the bulkof the side chain.

“Deletion” refers to modification to the polypeptide by removal of oneor more amino acids from the reference polypeptide. Deletions cancomprise removal of 1 or more amino acids, 2 or more amino acids, 5 ormore amino acids, 10 or more amino acids, 15 or more amino acids, or 20or more amino acids, up to 10% of the total number of amino acids, or upto 20% of the total number of amino acids making up the reference enzymewhile retaining enzymatic activity and/or retaining the improvedproperties of an engineered transaminase enzyme. Deletions can bedirected to the internal portions and/or terminal portions of thepolypeptide. In various embodiments, the deletion can comprise acontinuous segment or can be discontinuous.

“Insertion” refers to modification to the polypeptide by addition of oneor more amino acids from the reference polypeptide. In some embodiments,the improved engineered transaminase enzymes comprise insertions of oneor more amino acids to the naturally occurring transaminase polypeptideas well as insertions of one or more amino acids to other improvedtransaminase polypeptides. Insertions can be in the internal portions ofthe polypeptide, or to the carboxy or amino terminus. Insertions as usedherein include fusion proteins as is known in the art. The insertion canbe a contiguous segment of amino acids or separated by one or more ofthe amino acids in the naturally occurring polypeptide.

“Fragment” as used herein refers to a polypeptide that has anamino-terminal and/or carboxy-terminal deletion, but where the remainingamino acid sequence is identical to the corresponding positions in thesequence. Fragments can be at least 14 amino acids long, at least 20amino acids long, at least 50 amino acids long or longer, and up to 70%,80%, 90%, 95%, 98%, and 99% of the full-length transaminase polypeptide,for example the polypeptide of SEQ ID NO:2 or engineered transaminase ofSEQ ID NO:10.

“Isolated polypeptide” refers to a polypeptide which is substantiallyseparated from other contaminants that naturally accompany it, e.g.,protein, lipids, and polynucleotides. The term embraces polypeptideswhich have been removed or purified from their naturally-occurringenvironment or expression system (e.g., host cell or in vitrosynthesis). The improved transaminase enzymes may be present within acell, present in the cellular medium, or prepared in various forms, suchas lysates or isolated preparations. As such, in some embodiments, theimproved transaminase enzyme can be an isolated polypeptide.

“Substantially pure polypeptide” refers to a composition in which thepolypeptide species is the predominant species present (i.e., on a molaror weight basis it is more abundant than any other individualmacromolecular species in the composition), and is generally asubstantially purified composition when the object species comprises atleast about 50 percent of the macromolecular species present by mole or% weight. Generally, a substantially pure transaminase composition willcomprise about 60% or more, about 70% or more, about 80% or more, about90% or more, about 95% or more, and about 98% or more of allmacromolecular species by mole or % weight present in the composition.In some embodiments, the object species is purified to essentialhomogeneity (i.e., contaminant species cannot be detected in thecomposition by conventional detection methods) wherein the compositionconsists essentially of a single macromolecular species. Solventspecies, small molecules (<500 Daltons), and elemental ion species arenot considered macromolecular species. In some embodiments, the isolatedimproved transaminases polypeptide is a substantially pure polypeptidecomposition.

“Stringent hybridization” is used herein to refer to conditions underwhich nucleic acid hybrids are stable. As known to those of skill in theart, the stability of hybrids is reflected in the melting temperature(T_(m)) of the hybrids. In general, the stability of a hybrid is afunction of ion strength, temperature, G/C content, and the presence ofchaotropic agents. The T_(m) values for polynucleotides can becalculated using known methods for predicting melting temperatures (see,e.g., Baldino et al., Methods Enzymology 168:761-777; Bolton et al.,1962, Proc. Natl. Acad. Sci. USA 48:1390; Bresslauer et al., 1986, Proc.Natl. Acad. Sci. USA 83:8893-8897; Freier et al., 1986, Proc. Natl.Acad. Sci USA 83:9373-9377; Kierzek et al., Biochemistry 25:7840-7846;Rychlik et al., 1990, Nucleic Acids Res 18:6409-6412 (erratum, 1991,Nucleic Acids Res 19:698); Sambrook et al., supra); Suggs et al., 1981,In Developmental Biology Using Purified Genes (Brown et al., eds.), pp.683-693, Academic Press; and Wetmur, 1991, Crit Rev Biochem Mol Biol26:227-259. All publications incorporate herein by reference). In someembodiments, the polynucleotide encodes the polypeptide disclosed hereinand hybridizes under defined conditions, such as moderately stringent orhighly stringent conditions, to the complement of a sequence encoding anengineered transaminase enzyme of the present disclosure.

“Hybridization stringency” relates to hybridization conditions, such aswashing conditions, in the hybridization of nucleic acids. Generally,hybridization reactions are performed under conditions of lowerstringency, followed by washes of varying but higher stringency. Theterm “moderately stringent hybridization” refers to conditions thatpermit target-DNA to bind a complementary nucleic acid that has about60% identity, preferably about 75% identity, about 85% identity to thetarget DNA, with greater than about 90% identity totarget-polynucleotide. Exemplary moderately stringent conditions areconditions equivalent to hybridization in 50% formamide, 5×Denhart'ssolution, 5×SSPE, 0.2% SDS at 42° C., followed by washing in 0.2×SSPE,0.2% SDS, at 42° C. “High stringency hybridization” refers generally toconditions that are about 10° C. or less from the thermal meltingtemperature T_(n), as determined under the solution condition for adefined polynucleotide sequence. In some embodiments, a high stringencycondition refers to conditions that permit hybridization of only thosenucleic acid sequences that form stable hybrids in 0.018M NaCl at 65° C.(i.e., if a hybrid is not stable in 0.018M NaCl at 65° C., it will notbe stable under high stringency conditions, as contemplated herein).High stringency conditions can be provided, for example, byhybridization in conditions equivalent to 50% formamide, 5×Denhart'ssolution, 5×SSPE, 0.2% SDS at 42° C., followed by washing in 0.1×SSPE,and 0.1% SDS at 65° C. Another high stringency condition is hybridizingin conditions equivalent to hybridizing in 5×SSC containing 0.1% (w:v)SDS at 65° C. and washing in 0.1×SSC containing 0.1% SDS at 65° C. Otherhigh stringency hybridization conditions, as well as moderatelystringent conditions, are described in the references cited above.

“Heterologous” polynucleotide refers to any polynucleotide that isintroduced into a host cell by laboratory techniques, and includespolynucleotides that are removed from a host cell, subjected tolaboratory manipulation, and then reintroduced into a host cell.

“Codon optimized” refers to changes in the codons of the polynucleotideencoding a protein to those preferentially used in a particular organismsuch that the encoded protein is efficiently expressed in the organismof interest. Although the genetic code is degenerate in that most aminoacids are represented by several codons, called “synonyms” or“synonymous” codons, it is well known that codon usage by particularorganisms is nonrandom and biased towards particular codon triplets.This codon usage bias may be higher in reference to a given gene, genesof common function or ancestral origin, highly expressed proteins versuslow copy number proteins, and the aggregate protein coding regions of anorganism's genome. In some embodiments, the polynucleotides encoding thetransaminases enzymes may be codon optimized for optimal production fromthe host organism selected for expression.

“Preferred, optimal, high codon usage bias codons” refersinterchangeably to codons that are used at higher frequency in theprotein coding regions than other codons that code for the same aminoacid. The preferred codons may be determined in relation to codon usagein a single gene, a set of genes of common function or origin, highlyexpressed genes, the codon frequency in the aggregate protein codingregions of the whole organism, codon frequency in the aggregate proteincoding regions of related organisms, or combinations thereof. Codonswhose frequency increases with the level of gene expression aretypically optimal codons for expression. A variety of methods are knownfor determining the codon frequency (e.g., codon usage, relativesynonymous codon usage) and codon preference in specific organisms,including multivariate analysis, for example, using cluster analysis orcorrespondence analysis, and the effective number of codons used in agene (see GCG CodonPreference, Genetics Computer Group WisconsinPackage; CodonW, John Peden, University of Nottingham; McInerney, J. O,1998, Bioinformatics 14:372-73; Stenico et al., 1994, Nucleic Acids Res.222437-46; Wright, F., 1990, Gene 87:23-29). Codon usage tables areavailable for a growing list of organisms (see for example, Wada et al.,1992, Nucleic Acids Res. 20:2111-2118; Nakamura et al., 2000, Nucl.Acids Res. 28:292; Duret, et al., supra; Henaut and Danchin,“Escherichia coli and Salmonella,” 1996, Neidhardt, et al. Eds., ASMPress, Washington D.C., p. 2047-2066. The data source for obtainingcodon usage may rely on any available nucleotide sequence capable ofcoding for a protein. These data sets include nucleic acid sequencesactually known to encode expressed proteins (e.g., complete proteincoding sequences-CDS), expressed sequence tags (ESTS), or predictedcoding regions of genomic sequences (see for example, Mount, D.,Bioinformatics: Sequence and Genome Analysis, Chapter 8, Cold SpringHarbor Laboratory Press, Cold Spring Harbor, N.Y., 2001; Uberbacher, E.C., 1996, Methods Enzymol. 266:259-281; Tiwari et al., 1997, Comput.Appl. Biosci. 13:263-270).

“Control sequence” is defined herein to include all components, whichare necessary or advantageous for the expression of a polynucleotideand/or polypeptide of the present disclosure. Each control sequence maybe native or foreign to the nucleic acid sequence encoding thepolypeptide. Such control sequences include, but are not limited to, aleader, polyadenylation sequence, propeptide sequence, promoter, signalpeptide sequence, and transcription terminator. At a minimum, thecontrol sequences include a promoter, and transcriptional andtranslational stop signals. The control sequences may be provided withlinkers for the purpose of introducing specific restriction sitesfacilitating ligation of the control sequences with the coding region ofthe nucleic acid sequence encoding a polypeptide.

“Operably linked” is defined herein as a configuration in which acontrol sequence is appropriately placed (i.e., in a functionalrelationship) at a position relative to a polynucleotide of interestsuch that the control sequence directs or regulates the expression ofthe polynucleotide and/or polypeptide of interest.

“Promoter sequence” refers to a nucleic acid sequence that is recognizedby a host cell for expression of a polynucleotide of interest, such as acoding sequence. The promoter sequence contains transcriptional controlsequences, which mediate the expression of a polynucleotide of interest.The promoter may be any nucleic acid sequence which showstranscriptional activity in the host cell of choice including mutant,truncated, and hybrid promoters, and may be obtained from genes encodingextracellular or intracellular polypeptides either homologous orheterologous to the host cell.

“Alkyl” by itself or as part of another substituent refers to asaturated or unsaturated branched, straight-chain or cyclic monovalenthydrocarbon radical having the stated number of carbon atoms (e.g.,C₁-C₆ means one to six carbon atoms) that is derived by the removal ofone hydrogen atom from a single carbon atom of a parent alkane, alkeneor alkyne. The term “alkyl” is specifically intended to include groupshaving any degree or level of saturation, i.e., groups havingexclusively single carbon-carbon bonds, groups having one or more doublecarbon-carbon bonds, groups having one or more triple carbon-carbonbonds and groups having mixtures of single, double and triplecarbon-carbon bonds. Where a specific level of saturation is intended,the expressions “alkanyl,” “alkenyl,” and “alkynyl” are used. Theexpression “lower alkyl” refers to alkyl groups composed of from 1 to 6carbon atoms, preferably 1-4 carbon atoms.

“Alkanyl” by itself or as part of another substituent refers to asaturated branched, straight-chain or cyclic alkyl derived by theremoval of one hydrogen atom from a single carbon atom of a parentalkane. Alkanyl groups include, but are not limited to, methanyl;ethanyl; propanyls such as propan-1-yl, propan-2-yl (isopropyl),cyclopropan-1-yl, etc.; butanyls such as butan-1-yl, butan-2-yl(sec-butyl), 2-methyl-propan-1-yl (isobutyl), 2-methyl-propan-2-yl(t-butyl), cyclobutan-1-yl, etc.; and the like. In some embodiments, thealkanyl groups are (C₁-C₆) alkyl.

“Alkenyl” by itself or as part of another substituent refers to anunsaturated branched, straight-chain or cyclic alkyl having at least onecarbon-carbon double bond derived by the removal of one hydrogen atomfrom a single carbon atom of a parent alkene. The group may be in eitherthe cis or trans conformation about the double bond(s). Alkenyl groupsinclude, but are not limited to, ethenyl; propenyls such asprop-1-en-1-yl, prop-1-en-2-yl, prop-2-en-1-yl, prop-2-en-2-yl,cycloprop-1-en-1-yl; cycloprop-2-en-1-yl; butenyls such asbut-1-en-1-yl, but-1-en-2-yl, 2-methyl-prop-1-en-1-yl, but-2-en-1-yl,but-2-en-2-yl, buta-1,3-dien-1-yl, buta-1,3-dien-2-yl,cyclobut-1-en-1-yl, cyclobut-1-en-3-yl, cyclobuta-1,3-dien-1-yl, etc.;and the like. In some embodiments, the alkenyl group is (C₂-C₆) alkenyl.

“Alkynyl” by itself or as part of another substituent refers to anunsaturated branched, straight-chain or cyclic alkyl having at least onecarbon-carbon triple bond derived by the removal of one hydrogen atomfrom a single carbon atom of a parent alkyne. Typical alkynyl groupsinclude, but are not limited to, ethynyl; propynyls such asprop-1-yn-1-yl, prop-2-yn-1-yl, etc.; butynyls such as but-1-yn-1-yl,but-1-yn-3-yl, but-3-yn-1-yl, etc.; and the like. In some embodiments,the alkynyl group is (C₂-C₆) alkynyl.

“Cycloalkyl” and “Heterocycloalkyl” by themselves or as part of anothersubstituent refer to cyclic versions of “alkyl” and “heteroalkyl”groups, respectively. For heteroalkyl groups, a heteroatom can occupythe position that is attached to the remainder of the molecule. Typicalcycloalkyl groups include, but are not limited to, cyclopropyl;cyclobutyls such as cyclobutanyl and cyclobutenyl; cyclopentyls such ascyclopentanyl and cyclopentenyl; cyclohexyls such as cyclohexanyl andcyclohexenyl; and the like. Typical heterocycloalkyl groups include, butare not limited to, tetrahydrofuranyl (e.g., tetrahydrofuran-2-yl,tetrahydrofuran-3-yl, etc.), piperidinyl (e.g., piperidin-1-yl,piperidin-2-yl, etc.), morpholinyl (e.g., morpholin-3-yl,morpholin-4-yl, etc.), piperazinyl (e.g., piperazin-1-yl,piperazin-2-yl, etc.), and the like.

“Aryl” by itself or as part of another substituent refers to amonovalent aromatic hydrocarbon group having the stated number of carbonatoms (e.g., C₅-C₁₅ means from 5 to 15 carbon atoms) derived by theremoval of one hydrogen atom from a single carbon atom of a parentaromatic ring system. In some embodiments, the aryl group is (C₅-C₁₅)aryl, with (C₅-C₁₀) being even more preferred. In some embodiments, thearyls are cyclopentadienyl, phenyl and naphthyl.

“Heteroaryl” by itself or as part of another substituent refers to amonovalent heteroaromatic group having the stated number of ring atoms(e.g., “5-14 membered” means from 5 to 14 ring atoms) derived by theremoval of one hydrogen atom from a single atom of a parentheteroaromatic ring system. In some embodiments, the heteroaryl group isa 5-14 membered heteroaryl. In some embodiments, the heteroaryl group isa 5-10 membered heteroaryl.

“Alkoxy” by itself or as part of another substituent refers to —OR′,where R⁷ represents an alkyl or cycloalkyl group as defined herein.Typical alkoxy groups include, but are not limited to, methoxy, ethoxy,propoxy, butoxy, cyclohexyloxy, and the like.

“Alkylcarbonyl” by itself or as part of another substituent refers to—C(O)—R⁸, where R⁸ is an alkyl, as defined above. Typical alkoxycarbonylinclude, but are not limited to, acetyl, ethylcarbonyl,n-propylcarbonyl, and the like.

“Alkoxycarbonyl” by itself or as part of another substituent, refers toC(O)OR⁹ where R⁹ represents an alkyl or cyclalkyl group as definedherein. Typical alkoxycarbonyl groups include, but are not limited to,methoxycarbonyl, ethoxycarbonyl, proproxycarbonyl, butoxycarbonyl,cyclohexyloxycarbonyl, and the like.

“Amino” by itself or as part of another substituent refers to the group—NH₂. Substituted amino refers to the group —NHR¹⁰, NR¹⁰R¹⁰, andNR¹⁰R¹⁰R¹⁰, where each R¹⁰ is independently selected from substituted orunsubstituted alkyl, cycloalkyl, cycloheteroalkyl, alkoxy, aryl,heteroaryl, heteroarylalkyl, acyl, alkoxycarbonyl, sulfanyl, sulfinyl,sulfonyl, and the like. Typical amino groups include, but are limitedto, dimethylamino, diethylamino, trimethylamino, triethylamino,methylysulfonylamino, furanyl-oxy-sulfamino, and the like.

“Substituted alkyl, aryl, arylalkyl, heteroaryl or heteroarylalkyl”refers to an alkyl, aryl, arylalkyl, heteroaryl or heteroarylakyl groupin which one or more hydrogen atoms is replaced with another substituentgroup. Exemplary substituent groups include, but are not limited to,—OR¹¹, —SR¹¹, —NR¹¹R¹¹, —NO₂, —NO, —CN, —CF₃, halogen (e.g., —F, —Cl,—Br and —I), —C(O)R¹¹, —C(O)OR¹¹, —C(O)NR¹¹, —S(O)₂R¹¹, —S(O)₂NR¹¹R¹¹,where each R¹⁰ is independently selected from the group consisting ofhydrogen and (C₁-C₆) alkyl.

“Substituted” as used herein means one or more hydrogen atoms (e.g., 1,2, 3, 4, 5, or 6 hydrogen atoms) of the group is replaced with asubstituent atom or group commonly used in pharmaceutical chemistry.Each substituent can be the same or different. Examples of suitablesubstituents include, but are not limited to, alkyl, alkenyl, alkynyl,cycloalkyl, aryl, aralkyl, cycloheteroalkyl, heteroaryl, OR¹² (e.g.,hydroxyl, alkoxy (e.g., methoxy, ethoxy, and propoxy), aryloxy,heteroaryloxy, aralkyloxy, ether, ester, carbamate, etc.), hydroxyalkyl,alkoxycarbonyl, alkoxyalkoxy, perhaloalkyl, perfluoroalkyl (e.g., CF₃,CF₂, CF₃), perfluoroalkoxy (e.g., OCF₃, OCF₂CF₃), alkoxyalkyl, SR¹²(e.g., thiol, alkylthio, arylthio, 12-12 heteroarylthio, aralkylthio,etc.), S⁺R¹¹ ₂, S(O)R¹², SO₂R¹², NRR (e.g., primary amine (i.e., NH₂),secondary amine, tertiary amine, amide, carbamate, urea, etc.),hydrazide, halide, nitrile, nitro, sulfide, sulfoxide, sulfone,sulfonamide, thiol, carboxy, aldehyde, keto, carboxylic acid, ester,amide, imine, and imide, including seleno and thio derivatives thereof,wherein each of the substituents can be optionally further substituted.In embodiments in which a functional group with an aromatic carbon ringis substituted, such substitutions will typically number about 1 to 5,with about 1 or 2 substitutions being preferred.

6.3 Transaminase Enzymes

The present disclosure provides transaminase polypeptides having theability to catalyze the transfer of an amino group from a donor amine toan amine acceptor molecule, polynucleotides encoding such polypeptides,and methods for using the polypeptides. Transaminase polypeptides areuseful for the enantiomeric enrichment and stereoselective synthesis ofchiral amines.

The transaminase enzymes described herein are capable of catalyzing thetransfer of an amino group from an amino donor of general Formula II toan amino acceptor (ketone substrate) of general Formula I. The productsof this reaction are a chiral amine (III) having a stereogenic carbonatom indicated by the * and an amino acceptor (ketone) byproduct (IV),as shown in Scheme 1:

where the chiral carbon to which the amine is bonded has ispredominantly (S) or (R) stereochemistry. As such, the chiral amineproduct is produced in stereomeric excess.

In some embodiments, the transaminase enzymes described herein arecapable of catalyzing the transfer of an amino group from an amino donorof general Formula II to an amino acceptor (ketone substrate) of generalFormula I and stereoselectively forming a chiral amine (III₈) in whichthe chiral carbon to which the amine is bonded has predominately (S)stereochemistry, and an amino acceptor (ketone) byproduct (IV), as shownin Scheme 2:

In some embodiments, the transaminase enzymes described herein arecapable of catalyzing the transfer of an amino group from an amino donorof general Formula II to an amino acceptor (ketone) of general FormulaI, in which the products of the reaction are a chiral amine (III_(R))having predominately (R) stereochemistry, and an amino acceptor (ketone)byproduct (IV), as shown in Scheme 3:

Each of R¹, R², R³ and R⁴, when taken independently, can be an alkyl, analkylaryl group, or aryl group which is unsubstituted or substitutedwith one or more enzymatically non-inhibiting groups, where R¹ isdifferent from R² in structure or chirality, or R¹ and R², takentogether, are a hydrocarbon chain of 4 or more carbon atoms containing acenter of chirality. In some embodiments, the alkyl group can be asubstituted or unsubstituted branched or straight chain alkyl. R₃ may bethe same or different from R⁴ in structure or chirality. In someembodiments, R³ and R⁴, taken together, may form a ring that isunsubstituted, substituted, or fused to other rings. In someembodiments, the rings can be substituted or unsubstituted cycloalkyl orheterocycloalkyl. In some embodiments for R³ and R⁴, the alkyl, eitheralone or as a substituted or unsubstituted alkylaryl is a lower alkyl.

In general, the enzymatic process operates on only one chiral form of anamine, or operates on one chiral form to a far greater extent than theother. Thus, the transaminase polypeptides described herein are capableof performing stereoselective synthesis, in which one of the chiralamine products (III_(S) or III_(R)) illustrated above is produced in anamount substantially greater than the other. “Substantially greater” asused herein refers to a percentage of the combined amount of both chiralforms that is at least about 51% (e.g., at least 51, 55, 60, 65, 70, 75,80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99%). As such, in someembodiments, the product of the transaminase can be in a stereomericexcess of at least 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% 95%,96%, 97%, 98%, or 99% or greater.

Reactions shown in Schemes 1 to 3 use an amino acceptor substrate and anamino donor substrate. Amino acceptors are compounds of general FormulaI:

in which each of R¹, R², when taken independently, can be an alkyl, analkylaryl group, or aryl group which is unsubstituted or substitutedwith one or more enzymatically non-inhibiting groups. As noted above, R¹may be the same or different from R² in structure or chirality. In someembodiments, R¹ and R², taken together, may form a ring that isunsubstituted, substituted, or fused to other rings. In someembodiments, the amino acceptor is any compound according to Formula I,above.

Amino donors are compounds of general Formula II:

in which each of R³, R⁴, when taken independently, is an alkyl, analkylaryl group, or aryl group which is unsubstituted or substitutedwith one or more enzymatically non-inhibiting groups. R₃ may be the sameor different from R₄ in structure or chirality. R³ and R⁴, takentogether, may form a ring that is unsubstituted, substituted, or fusedto other rings. In some embodiments for R³ and R⁴, the alkyl, eitheralone or as a substituted or unsubstituted alkylaryl is a lower alkyl.The amino donors can include all salt forms of the compounds of FormulaII.

In some embodiments, the amino donor is any compound according toFormula II, above and all possible salt forms. Exemplary amino donorsinclude, among others, isopropylamine (2-amino propane), D-alanine,L-alanine, or D,L-alanine, and all possible salts of these amino donors.

As illustrated, the reaction can proceed in either the forward orreverse direction. In some embodiments, either the forward or reversereactions can be favored by adding or removing starting materials orreaction products. For example, when one stereoselectively synthesizesone chiral form of an amine (III_(S) or III_(R)), as shown in ReactionsI and II, additional amino acceptor (ketone) or amino donor can be added(up to saturation) and/or the chiral amine or ketone by product formedcan be removed.

For performing the transamination reactions, the present disclosureprovides engineered transaminase enzymes that are capable ofstereoselectively converting an amino acceptor to the correspondingchiral amino product and which have an improved property when comparedwith the naturally-occurring enzyme obtained from Vibrio fluvialis (SEQID NO:2) or when compared with other engineered transaminase enzymes(e.g., SEQ ID NO:18).

In the characterizations of the transaminases herein, the polypeptidescan be described in reference to the amino acid sequence of a naturallyoccurring transaminase of Vibrio fluvialis or another engineeredtransaminase. As such, the amino acid residue position is determined inthe transaminases beginning from the initiating methionine (M) residue(i.e., M represents residue position 1), although it will be understoodby the skilled artisan that this initiating methionine residue may beremoved by biological processing machinery, such as in a host cell or invitro translation system, to generate a mature protein lacking theinitiating methionine residue. The amino acid residue position at whicha particular amino acid or amino acid change is present in an amino acidsequence is sometimes describe herein in terms “Xn”, or “position n”,where n refers to the residue position. A substitution mutation, whichis a replacement of an amino acid residue in a reference sequence with adifferent amino acid residue may be denoted by the symbol “→”, or byconventional notations used in the art, for example, Y(number)Z, where Yis the amino acid residue in the reference sequence, the “number” refersto the residue position, and Z is the amino residue substitution.

The polynucleotide sequence encoding the naturally occurringtransaminase of Vibrio fluvialis JS17 is described in Shin et al., 2003,“Purification, characterization, and molecular cloning of a novelamine:pyruvate transaminase from Vibrio fluvialis JS17” Appl MicrobiolBiotechnol. 61(5-6):463-471). The polynucleotide and amino acid sequenceof the Vibrio fluvialis transaminase is also presented herein as SEQ IDNO:1 and SEQ ID NO:2, respectively.

As noted above, the transaminases of the disclosure are characterized byan improved enzyme property as compared to the naturally occurringparent enzyme or another engineered transaminase polypeptide. In theembodiments herein, the improved property of the transaminase can bewith respect to, among others, enzyme activity, stability (e.g.,solvent- and/or thermostability), stereoselectivity, stereospecificity,inhibitor resistance, and substrate recognition. In some embodiments,the transaminase polypeptides can have more than one improved property,such as increased stability and substrate recognition.

In some embodiments, the engineered transaminases have various residuedifferences as compared to a reference sequence (e.g.,naturally-occurring polypeptide of SEQ ID NO:2 or an engineeredpolypeptide of SEQ ID NO:18) that result in changes to the enzymeproperties. The residue differences can be characterized as“modifications” of the reference sequence, where the modificationsinclude amino acid substitutions, deletions, and insertions. Any one ora combination of modifications can be present to generate the improvedengineered transaminases. These residue differences can also bedescribed as particular features of the improved engineered polypeptidesat specified residue positions.

In some embodiments, the number of residue differences from thereference transaminase polypeptide that provides an improvedtransaminase property can comprise differences at one or more residuepositions, 2 or more residue positions, 3 or more residue positions, 5or more residue positions, 10 or more residue positions, or 20 or moreresidue positions, up to 10% of the total number of amino acids, up to20% of the total number of amino acids, or up to 30% of the total numberof amino acids of the reference enzyme sequence. In some embodiments,the number of residue differences as compared to the reference sequencecan be about 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-15, 1-20,1-21, 1-22, 1-23, 1-24, 1-25, 1-30, 1-35, 1-40, 1-45, 1-50, 1-55, or1-60 residue positions. In some embodiments, the number of differencesas compared to the reference sequence can be 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 30, 30, 35, 40, 45, 50,55, or 60 residue positions.

In some embodiments, the residue differences comprise substitutions ascompared to the reference sequence. In some embodiments, thesubstitutions as compared to the reference sequence can be at one ormore residue positions, 2 or more residue positions, 3 or more residuepositions, 5 or more residue positions, 10 or more residue positions, or20 or more residue positions, up to 10% of the total number of aminoacids, up to 20% of the total number of amino acids, or up to 30% of thetotal number of amino acids of the reference enzyme sequence. In someembodiments, the number of substitutions as compared to the referencesequence can be substitutions about 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8,1-9, 1-10, 1-15, 1-20, 1-21, 1-22, 1-23, 1-24, 1-25, 1-30, 1-35, 1-40,1-45, 1-50, 1-55, or 1-60 residue positions. In some embodiments, thenumber of substitutions as compared to the reference sequence can be 1,2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,30, 30, 35, 40, 45, 50, 55, or 60 residue positions.

In some embodiments, the residue differences of the engineeredtransaminases of the disclosure can occur at one or more of thefollowing residue positions: X4, X9, X12, X21, X30, X31, X44, X45, X,56, X57, X81, X82, X85, X86, X95, X112, X113, X127, X147, X153, X157,X166, X177, X181, X208, X211, X228, X233, X253, X272, X294, X297, X302,X311, X314, X316, X317, X318, X319, X320, X321, X324, X385, X391, X398,X407, X408, X409, X415, X417, X418, X420, X431, X434, X438, X444, andX446. As described herein, the presence of particular amino acidresidues at these residue positions is associated with changes toproperties of the transaminases. In some embodiments, the number ofresidue differences can be at least 2, 3, 4, 5, or 6 or more of thespecified residue positions.

In some embodiments, the choice of amino acid residues for the specifiedresidue positions can be based on the following features. X4 is a basicresidue; X9 is a polar residue; X12 a non-polar residue; X21 is a polarresidue; X30 is an aliphatic or non-polar residue; X31 is an aliphaticor non-polar residue; X44 is an aliphatic or non-polar residue; X45 is aconstrained residue; X56 is a non-polar or aliphatic residue; X57 is anaromatic, aliphatic, non-polar, polar or cysteine residue; X81 is anacidic residue; X82 is an aromatic or constrained residue; X85 is analiphatic, non-polar, polar, or cysteine residue; X86 is a constrained,aromatic, or polar residue; X95 is a polar residue; X112 is a non-polaror aliphatic residue; X113 is a cysteine, aromatic or constrainedresidue; X127 is an aliphatic or non-polar residue; X147 is a non-polarresidue; X153 is an aliphatic, non-polar, or polar residue; X157 is apolar residue; X166 is a polar residue; X177 is a non-polar or aliphaticresidue; X181 is a basic residue; X208 is a non-polar or aliphaticresidue; X211 is an acidic residue; X228 is a non-polar residue; X233 isa polar or aliphatic residue; X253 is a non-polar residue; X272 is anon-polar or aliphatic residue; X294 is a non-polar or aliphaticresidue; X297 is an aliphatic residue; X302 is an acidic residue; X311is an aliphatic residue; X314 is an aliphatic or polar residue; X316 isan acidic residue; X317 is an aromatic, non-polar or aliphatic residue;X318 is an aromatic, basic or non-polar residue; X319 is a non-polar,aliphatic, or polar residue; X320 is an aliphatic residue; X321 is analiphatic residue; X324 is a non-polar residue; X385 is a basic residue;X398 is a basic residue; X407 is a polar residue; X408 is an aliphaticresidue; X409 is non-polar residue; X415 is a non-polar residue; X417 isa non-polar, aliphatic, polar, acidic, or cysteine residue; X418 is anon-polar or aliphatic residue; X420 is a polar residue; X431 is anacidic residue; X434 is an aliphatic residue; X438 is an aliphaticresidue; X444 is a non-polar or aliphatic residue; and X446 is anon-polar or aliphatic residue. In some embodiments, where the aminoacid residue at the corresponding residue position of the referencesequence are encompassed within the category of amino acids describedfor the specified position, a different amino acid within that aminoacid category can be used in light of the guidance provided herein.

In some embodiments, the transaminase polypeptides can have additionallyone or more residue differences at residue positions not specified by anX above as compared to a reference sequence, for example SEQ ID NO:2. Insome embodiments, the differences can be 1-2, 1-3, 1-4, 1-5, 1-6, 1-7,1-8, 1-9, 1-10, 1-15, 1-20, 1-21, 1-22, 1-23, 1-24, 1-25, 1-30, 1-35,1-40, 1-45, 1-50, 1-55, or 1-60 residue differences at other amino acidresidue positions not defined by X above. In some embodiments, thenumber of differences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 16, 17,18, 19, 20, 21, 22, 23, 24, 25, 30, 30, 35, 40, 45, 50, 55, or 60residue differences at other amino acid residue positions. In someembodiments, the differences comprise conservative mutations.

In some embodiments, the amino acid residues at the specified positionscan be selected from one or more of the following features: X4 is R; X9is T; X12 is G; X21 is N; X30 is A; X31 is A; X44 is A; X45 is H; X56 isV; X57 is L, I, F, A, S, or C; X81 is D; X82 is H; X85 is A, S, V, T, N,or C; X86 is S, H, N, F, G, or A; X95 is T; X112 is I; X113 is H or C;X127 is L; X147 is G; X153 is A, S T, N, G, Q, or C; X157 is T; X166 isS; X177 is L; X181 is R; X208 is I; X211 is K; X228 is G; X233 is T, Sor L; X253 is M; X272 is A; X294 is V; X297 is A; X302 is K; X311 is V;X314 is V or T; X316 is K; X317 is L, Y or M; X318 is G, R, or F; X319is V or Q; X320 is A; X321 is L; X324 is G; X385 is R; X391 is A; X398is R; X407 is S; X408 is A; X409 is G; X415 is M; X417 is F, A, I, C, T,S, or C; X418 is V; X420 is N; X431 is D; X434 is V; X438 is L; X444 isV; and X446 is V. In some embodiments, the transaminase polypeptides canhave additionally one or more residue differences at residue positionsnot specified by an X above as compared to a reference sequence, forexample SEQ ID NO:2. In some embodiments, the differences can be 1-2,1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-15, 1-20, 1-21, 1-22, 1-23,1-24, 1-25, 1-30, 1-35, 1-40, 1-45, 1-50, 1-55, or 1-60 residuedifferences at other amino acid residue positions not defined by Xabove. In some embodiments, the number of differences can be 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 30, 30,35, 40, 45, 50, 55, or 60 residue differences at other amino acidresidue positions. In some embodiments, the differences compriseconservative mutations. In some embodiments, the engineeredtransaminases can comprise an amino acid sequence that is at least 80%,85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%,99%, or more identical to a reference based on SEQ ID NO:2 having one ormore of the preceding features, and is characterized one or more of theimproved enzyme properties described herein.

In some embodiments, the improved transaminase polypeptides comprise anamino acid sequence having at least one or more residue differences ascompared to the reference sequence, e.g., naturally occurring sequenceof SEQ ID NO:2 or an engineered transaminase sequence of SEQ ID NO:18,at the following residue positions: X57, X85, X86, X153, X228, X233,X317, X318, and X417. In some embodiments, the residues at these residuepositions can be selected from the following features: X57 is anaromatic, aliphatic, non-polar, polar or cysteine residue; X85 is analiphatic, non-polar, polar, or cysteine residue; X86 is a constrained,aromatic, or polar residue; X153 is an aliphatic, non-polar, or polarresidue; X228 is a non-polar residue; X233 is a polar or aliphaticresidue; X317 is an aromatic, non-polar or aliphatic residue; X318 is anaromatic, basic or non-polar residue; and X417 is a non-polar,aliphatic, polar, acidic, or cysteine residue. In some embodiments, theresidues at these residue positions can be selected from the followingfeatures: X57 is L, I, F, A, S, or C; X85 is A, S, V, T, N, or C; X86 isS, H, N, F, G, or A; X153 is A, S T, N, G, Q, or C; X228 is G; X233 isT, S or L; X317 is L, Y or M; X318 is G, R, or F; and X417 is F, A, I,C, T, S, or C. In some embodiments, the engineered transaminases cancomprise an amino acid sequence that is at least 80%, 85%, 86%, 87%,88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or moreidentical to a reference based on SEQ ID NO:2 having one or more of thepreceding features, and is characterized one or more of the improvedenzyme properties described herein.

In some embodiments, the improved transaminase polypeptide can comprisean amino acid sequence that is at least 80%, 85%, 86%, 87%, 88%, 89%,90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or more identical to asequence corresponding to SEQ ID NO: 4, 6, 8, 10, 16, 18, 20, 22, 24,26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60,62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88. 90, 92, 94, 96,98, 100, 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 122, 124,126, 128, 130, 132, 134, 136, 138, 140, 142, 144, 146, 148, 150, 152,154, 156, 158, 160, 162, 164, 166, 168, 170. 172, 174, 176, 178, 180,182, 184, 186, 188, 190, 192, 194, 196, or 198. In some of theseembodiments, the transaminase polypeptides can have one or more of theimproved properties described herein.

In some embodiments, the improved transaminase polypeptides comprises anamino acid sequence corresponding to the sequence of SEQ ID NO: 4, 6, 8,10, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48,50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84,86, 88. 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116,118, 120, 122, 124, 126, 128, 130, 132, 134, 136, 138, 140, 142, 144,146, 148, 150, 152, 154, 156, 158, 160, 162, 164, 166, 168, 170. 172,174, 176, 178, 180, 182, 184, 186, 188, 190, 192, 194, 196, or 198.

In some embodiments, the improved property of the transaminasepolypeptide is with respect to its stability, such as thermostabilityand/or solvent stability. It is advantageous for transaminasepolypeptides to be able to retain enzymatic activity at elevatedtemperatures and solvent conditions in order to drive the reaction tocompletion. For example, the transaminase polypeptide of SEQ ID NO:2 maylose activity at elevated temperature (e.g., 40-45° C.) or in presenceof reaction components, e.g., amine donor isopropylamine. In someembodiments, the thermostable polypeptides of the disclosure arecharacterized by higher retention of activity when treated for about 0.5to 24 hours at about 35° C. to 50° C., at a pH of about 7.5 to 9.0, ascompared to transaminase of SEQ ID NO:2. In some embodiments, the amountof enzymatic activity remaining, i.e., residual activity, followingtreatment at the defined elevated temperature can be at least 5%, 10%,20%, 30%, 40%, 50% or more of the activity of an untreated polypeptideas assayed at a defined condition. In some embodiments, the elevatedtemperature condition is 50° C. for 23 hrs. Under the latter condition,the naturally-occurring transaminase of SEQ ID NO:2 has no residualactivity following treatment at the defined condition while theengineered transaminases of the disclosure retains significant activity.For example, the transaminase of SEQ ID NO:16 or 18 following treatmentat 50° C. for 23 hrs is capable of converting 10% and 23%, respectively,of the substrate pyruvate to product alanine in presence of amino donorisopropylamine, under the assay condition described in the Examples.

In some embodiments, the engineered transaminase polypeptides arecharacterized by resistance against inactivation by a solvent orreaction component, e.g., isopropylamine. In some embodiments, theengineered transaminase enzymes are resistant to inactivation by up to 1M or by up to 2 M isopropylamine. In some embodiments, the amount ofenzymatic activity remaining, i.e., residual activity, followingtreatment with solvent or reaction component (e.g., isopropylamine) canbe at least 5%, 10%, 20%, 30%, 40%, 50% or more of the activity of anuntreated polypeptide.

In some embodiments, the improved transaminase polypeptide characterizedby increased thermo- and/or solvent stability comprises an amino acidsequence that is at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%,97%, 98%, 99% or more identical to the sequence of SEQ ID NO: 10, 16, or18. In some embodiments, the transaminase polypeptide characterized byincreased thermostability corresponds to the sequence of SEQ ID NO: 10,16, or 18.

In some embodiments, the transaminase polypeptides having improvedthermostability (as compared to SEQ ID NO:2) can have residuedifferences as compared to SEQ ID NO:2 at one or more of the followingresidue positions: X4, X9, X12, X21, X45, X86, X157, X177, X208, X211,X253, X272, X294, X302, X316, X324, X391, X398, X418, X420, X431, X444,and X446. In some embodiments, the number of residue differences can beat least 2, 3, 4, 5, or 6 or more of the specified residue positionsassociated with increased thermostability.

In some embodiments, the transaminase polypeptides improved as comparedto SEQ ID NO:2 with respect to their thermostability have one or more ofthe following features: X4 is R, Q, or L; X9 is T; X12 is K; X21 is N;X45 is H; X86 is Y; X157 is T; X177 is L; X208 is I; X211 is K; X253 isM; X272 is A; X294 is V; X302 is K; X316 is K; X324 is G; X391 is A;X398 is R; X418 is V; X420 is N; X431 is D; X444 is V; and X446 is V.

In some embodiments, the improved transaminase polypeptide characterizedby increased thermostability includes, but are not limited to, an aminoacid sequence having one of the following feature or set of features:X45 is H, X86 is Y, X177 is L, X211 is K, X294 is V, X324 is G, X391 isA, X398 is R, and X420 is N; X9 is T, X45 is H, X86 is Y, X177 is L,X211 is K, X294 is V, X324 is G, and X391 is A; X21 is N, X45 is H, X177is L, X208 is I, X211 is K, X324 is G, X391 is A; and X9 is T, X21 is N,X86 is Y, X208 is I, and X294 is V.

In some embodiments, the transaminase polypeptide is improved withrespect to, among other properties, enzyme activity, substraterecognition, stereospecificity and/or stereoselectivity. Thesecharacteristics can be present in the context of a thermo- and/orsolvent stable engineered transaminase, such as SEQ ID NO: 10, 16 or 18.For example, the thermo/solvent stable transaminases can be modified tohave improvements in other enzyme properties while retaining itsthermo/solvent stable characteristics. A significant advantage of havinga thermo- and/or solvent stable transaminase as a basis for obtainingimprovements in other enzyme properties, e.g., substrate recognition,enzyme activity, stereoselectivity, stereospecificity, is that theengineered transaminase can be used under a process condition that isunsuitable for the naturally occurring enzyme, for example, amongothers, (a) screening for activity on various substrates at conditionsof elevated temperature and/or high solvent concentrations; (b) scale-upconditions where transamination reactions may be carried out for longertime periods, and/or (c) under high substrate loading conditions. Insome embodiments, screening with substrates at the elevated temperatureand/or higher solvent concentration maintains the thermo- and/or solventstable features of the transaminase polypeptide while allowing foridentification of improvements in other enzyme properties.

However, in some embodiments, the improvements in other enzymeproperties can be in the context of the naturally occurring transaminasepolypeptide, such as the sequence of SEQ ID NO:2. Accordingly, in someembodiments, the engineered transaminase polypeptides characterized byimprovements in enzyme activity, substrate recognition orstereoselectivity can comprise an amino acid sequence that is at least80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or moreidentical to the sequence of SEQ ID NO:2 and having the indicatedimproved property.

In some embodiments, the improved property of the transaminasepolypeptide is with respect to an increase in its rate of conversion ofthe substrate to the product. This improvement in enzymatic activity canbe manifested by the ability to use less of the improved polypeptide ascompared to the wild-type (SEQ ID NO:2), or other reference sequence(e.g., SEQ ID NO:18), to produce the same amount of product in a givenamount of time. In some embodiments, the improvement in enzymaticactivity can be manifested by the ability to convert a greaterpercentage of the substrate to product in a defined time with the sameamount of enzyme as compared to the wild type or reference enzyme. Insome embodiments, the transaminase polypeptides are capable ofconverting the substrate to products at a rate that is at least1.1-fold, 1.5 fold, 2 fold, 3 fold, 4 fold, 5-fold, 10-fold, 25-fold,50-fold, 75-fold, 100-fold, 150-fold, 200-fold, 250-fold, 300-fold,500-fold, 1000-fold or more over the rate of SEQ ID NO:2 or SEQ IDNO:18.

In some embodiments, the transaminase polypeptides characterized byimproved enzymatic activity, i.e., greater rate of converting thesubstrates to products as compared to SEQ ID NO:2 and/or SEQ ID NO:18,can comprise an amino acid sequence having one or more of the followingfeatures: X30 is A; X31 is A; X44 is A; X45 is N; X56 is V; X57 is, A,C, F, I, L, or S; X81 is D; X82 is H; X85 is A, C, S, N, T, G, or V; X86is F, S, N, A, G, or H; X95 is T; X112 is I; X113 is C or H; X127 is L;X147 is G; X153 is A, C, G, N, M, Q, S, or T; X166 is S; X177 is V; X181is R; X208 is I; X211 is R; X228 is G or T; X233 is L, S, I, V, N, G, orT; X294 is M; V297 is A, S, T, I, M, Q, C, or G; X311 is V; X314 is T orV; X317 is L, M, or Y; X318 is G, F, C, K, W, or R; X319 is Q, G, M, N,or V, X320 is A or K; X321 is L, M, or I; X324 is S; X385 is R; X398 isR; X407 is S; X408 is A; X409 is G; X415 is M; X417 is A, C, E, F, I, N,Q, Y, S, T, or V; X420 is N; X434 is V; and X438 is L.

In some embodiments, transaminase polypeptides that are capable of anincreased enzymatic activity can comprise an amino acid sequence havingone or more of the following features: X30 is A; X31 is A; X56 is V; X81is D; X82 is H; X95 is T; X113 is C or H.

In some embodiments, the transaminase polypeptides that are improved ascompared to SEQ ID NO:2, and/or SEQ ID NO:18 with respect to their rateof enzymatic activity, e.g., their rate of converting the substrates toproducts can comprise an amino acid sequence having one of the followingset of features: X12 is G and X434 is V; X44 is A and X166 is S; X57 isI and X153 is S; X81 is D and X86 is H; X82 is H and X417 is F; X85 is Aand X317 is L; X85 is S and X153 is A; X85 is A and X153 is A; X85 is Sand X153 is S. X86 is S and X153 is S; X86 is H and X153 is A; X112 is Iand X317 is L; or X113 is H and X407 is S; X153 is S and X233 is S; X311is V and X314 is T; X314 is V and X409 is G; and X318 is G and X408 isA.

In some embodiments, the transaminase polypeptides that are improved ascompared to SEQ ID NO:2, and/or SEQ ID NO:18 with respect to their rateof enzymatic activity, i.e., their rate of converting the substrates toproducts can comprise an amino acid sequence having at least one of thefollowing set of features: X57 is A, X153 is S and X318 is G; X57 is F,X86 is H and X153 is Q; X57 is I, X86 is F and X320 is A; X57 is F, X86is F and X153 is Q; X57 is A, X153 is C and X321 is L; X57 is C, X86 isS and X417 is T; X57 is C, X86 is A and X317 is L; X57 is F, X318 is Fand X417 is S; X57 is L, X86 is S and X153 is A; X57 is F, X318 is G andX417 is I; X57 is L, X86 is F and X318 is F; X57 is L, X417 is C andX438 is L; X57 is F, X127 is L and X417 is C; X57 is S, X233 is L andX417 is V; X57 is S, X86 is G and X417 is C; X85 is A, X147 is G andX153 is A; X85 is S, X153 is A and X233 is T; X85 is A, X153 is S andX417 is S; X86 is H, X153 is A and X417 is C; X86 is H, X153 is S andX417 is C; X86 is F, X153 is C and X297 is A; X86 is S, X153 is T andX297 is A; X86 is H, X233 is L and X417 is A; X86 is F, X318 is R andX417 is A; X86 is N, X228 is G and X317 is L; X95 is T, X153 is A andX417 is C; X113 is C, X385 is R and X417 is C; X153 is A, X317 is L andX318 is G; X153 is A, X233 is T and X417 is C; X153 is S, X318 is R andX417 is E; X153 is C, X233 is L and X318 is R; X153 is T, X228 is G andX321 is L; X153 is S, X317 is L and X417 is C; X153 is T, X319 is V andX417 is I; X153 is S, X228 is G and X417 is V; X153 is C, X317 is Y andX319 is Q; X153 is T, X228 is G and X417 is A; X228 is G, X317 is L andX417 is C; X228 is G, X318 is G and X417 is C; X233 is L, X321 is L andX417 is I; and X317 is L, X318 is R and X417 is T.

In some embodiments, the transaminase polypeptides that are improved ascompared to SEQ ID NO:2 and/or SEQ ID NO:18 with respect to their rateof enzymatic activity, i.e., their rate of converting the substrates toproducts, can comprise an amino acid sequence having one the followingset of features: X57 is L and X86 is F and X153 is S and X233 is T andX417 is T; X86 is H and X153 is A and XA228 is G and X417 is I; and X86is H and X153 is S and X181 is R and X417 is T.

In some embodiments, the transaminase polypeptides described herein arecapable of stereoselectively converting amino acceptor substrates to thecorresponding chiral amine products, at a rate that is greater than thewild-type transaminase of Vibrio fluvialis (SEQ ID NO:2). Polypeptidesthat are capable of the above reaction include, but are not limited to,a polypeptide comprising an amino acid sequence corresponding to SEQ IDNO:18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50,52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86,88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116,118, 120, 122, 124, 126, 128, 130, 132, 134, 136, 138, 140, 142, 144,146, 148, 150, 152, 154, 156, 158, 160, 162, 164, 166, 168, 170, 172,174, 176, 178, 180, 182, 184, 186, 188, 190, or 192. Activities of theengineered transaminases with respect to specific substrates aredescribed in further detail below.

In some embodiments, the improved property of the transaminasepolypeptide is with respect to an increase of its stereoselectivity forconverting the amino acceptor substrate to a chiral amino product. Insome embodiments, the improved property of the transaminase is withrespect to an increase in stereoselectivity, i.e., herein, an increasein the stereomeric excess of the product. In some embodiments, theimproved property of the transaminase property is with respect toproducing the S enantiomers of chiral amines in stereomeric excess. Insome embodiments, the improved property of the transaminase property iswith respect to producing the R enantiomers of chiral amines instereomeric excess.

In some embodiments, the transaminase polypeptides are characterized bythe ability to convert amino acceptor substrates to the chiral amineproducts of the (R) configuration in stereomeric excess greater than thepolypeptide of SEQ ID NO:18. In some embodiments, the R-selectivetransaminase polypeptides comprise an amino acid sequence having one ormore of the following features: X57 is L; X81 is D; X82 is H; X85 is A,C, N, T, or V; X86 is S, F, or H; X95 is T; X112 is I; X147 is G; X153is A, S, N, G, or T; X233 is S or T; X317 is L, X318 is G or R; and X319is V.

In some embodiments, the transaminase polypeptides capable of convertingamino acceptor substrates to the chiral amine products of predominatelythe (R) configuration at a rate that is greater than the thermostablepolypeptide of SEQ ID NO:18 can comprise an amino acid sequence havingone of the following features: X85 is A; X85 is A and X153 is A; and X85is S and X153 is A.

In some embodiments, the transaminase polypeptide capable of convertingamino acceptor substrates to the chiral amine products of predominatelythe (R) configuration at a rate that is greater than the polypeptide ofSEQ ID NO:18 comprises an amino acid sequence, corresponding to SEQ IDNO: 22, 30, 32, 34, 36, 40, 44, 48, 56, 58, 60, 62, 64, 66, 68, 70, 72,76, 84, 88, 90, 92, 104, 108, 110, 120, 122, 124, 126, 128, 132, 160, or176.

In some embodiments, the transaminase polypeptide capable of convertingamino acceptor substrates to the chiral amine products of predominatelythe (R) configuration at a rate that is greater than the thermostablepolypeptide of SEQ ID NO:18 comprises an amino acid sequencecorresponding to SEQ ID NO: 32, 36, 40, 56, 58, 60, 62, 64, 66, 122,124, 126, 128, or 132

In some embodiments, the transaminase polypeptide capable of convertingamino acceptor substrates to the chiral amine products of predominatelythe (R) configuration, at a rate that is greater than the thermostablepolypeptide of SEQ ID NO:18 comprises an amino acid sequencecorresponding to SEQ ID NO: 122, 124, 126, 128, 130, or 132.

In some embodiments, the engineered transaminase polypeptides arecapable of binding and converting structurally diverse substrates. Insome instances, the conversion rates for structurally differentsubstrates for the naturally occurring V fluvialis enzyme may beinsignificant. Accordingly, in some embodiments, the engineeredtransaminase polypeptides are characterized by increased conversionrates for substrates that are not converted at significant rates by thepolypeptide of SEQ ID NO:2 or another engineered transaminase, such asSEQ ID NO:18.

In some embodiments, the transaminase polypeptides are characterized bythe capability of stereoselectively converting the substrate3,4-dihydronaphthalen-1(2H)-one, to the product(S)-1,2,3,4-tetrahydronaphthalen-1-amine, as below,

at a rate that is greater than the polypeptide of SEQ ID NO:2 and/or SEQID NO:18. Residue positions associated with increase in activity onsubstrate 3,4-dihydronaphthalen-1(2H)-one include one or more of thefollowing: X30, X44, X57, X82, X85, X113, X153, X166, X233, X314, X311,X317, X318, X319, X320; X407, X409, and X417.

In some embodiments, the transaminase polypeptides capable of converting3,4-dihydronaphthalen-1(2H)-one to(S)-1,2,3,4-tetrahydronaphthalen-1-amine at a rate greater than SEQ IDNO:2 or SEQ ID NO:18 comprises an amino acid sequence having at leastone or more of the following features or set of features: X30 is A; X31is A; X57 is I; X82 is H; X85 is V; X85 is C; X153 is S; X317 is M; X317is Y; X417 is A; X319 is Q; X320 is A; X417 is I; X113 is H and X407 isS; X44 is A and X166 is S; X314 is V and X409 is G; X153 is S and X233is S; X311 is V and X314 is T; X153 is S, X318 is R and X417 is E; X153is C, X233 is L and X318 is R; X153 is S, X317 is L and X417 is C; X233is L, X321 is L, and X417 is I; and X153 is C, X317 is Y and X319 is Q.

In some embodiments, the transaminase polypeptides capable of converting3,4-dihydronaphthalen-1(2H)-one to(S)-1,2,3,4-tetrahydronaphthalen-1-amine at a rate greater than SEQ IDNO:2 and/or SEQ ID NO:18 comprises an amino acid sequence correspondingto SEQ ID NO: 38, 42, 44, 52, 56, 66, 74, 76, 78, 80, 82, 84, 94, 96,98, 100, 104, 118, 160, 164, 172, 184, or 188.

In some embodiments, the transaminase polypeptide is capable ofstereoselectively converting 3,4-dihydronaphthalen-1(2H)-one to(S)-1,2,3,4-tetrahydronaphthalen-1-amine at a rate that is at least5-fold or greater than the polypeptide of SEQ ID NO:2 and/or SEQ IDNO:18. Polypeptides that are capable of the above reaction include, butare not limited to, a polypeptide comprising an amino acid sequencecorresponding to SEQ ID NO: 44, 104, 164, 172, 184, or 188.

In some embodiments, the transaminase polypeptide is capable ofstereoselectively converting 3,4-dihydronaphthalen-1(2H)-one to(S)-1,2,3,4-tetrahydronaphthalen-1-amine at a rate that is at least 10fold greater than the polypeptide of SEQ ID NO:2 and/or SEQ ID NO:18.Polypeptides that are capable of the above reaction include, but are notlimited to, a polypeptide comprising an amino acid sequencecorresponding to SEQ ID NO: 164 or 188.

In some embodiments, the transaminase polypeptide is capable ofstereoselectively converting the substrate 1-phenylbutan-2-one to theproduct (S)-1-phenylbutan-2-amine, as below

at a rate that is greater than the polypeptide of SEQ ID NO:2 and/or SEQID NO:18. Residue positions associated with increase in activity onsubstrate 1-phenylbutan-2-one include one or more of the following: X57;X81, X86; X153; X181; X228; X233; X317; X318; X319; X321; and X417.

In some embodiments, the transaminase polypeptides capable of converting1-phenylbutan-2-one, to the product (S)-1-phenylbutan-2-amine at a ratethat is greater than the wild-type Vibrio fluvialis (SEQ ID NO:2)comprise an amino acid sequence having at least one of the followingfeatures or set of features: X81 is D and X86 is H; X86 is H and X153 isA; X86 is H, X153 is A and X417 is C; X86 is H, X153 is S and X417 is C;X86 is H, X153 is A, X228 is G and X417 is I; X86 is H, X153 is S, X181is R and X417 is T; X228 is G, X317 is L and X417 is C; X57 is A, X153is S and X318 is G; X57 is F, X86 is H, and X153 is Q; X57 is A X153 isC and X321 is L; X86 is F, X318 is R and X417 is A; X228 is G, X318 is Gand X417 is C; X153 is S, X318 is R and X417 is E; X153 is C, X233 is Land X318 is R; X86 is N, X228 is G and X317 is L; X153 is T, X228 is Gand X321 is L; X153 is S, X317 is L, X417 is C; X57 is L, X86 is S andX153 is A; X153 is S, X228 is G and X417 is V; X153 is C, X317 is Y andX319 is Q; and X153 is T, X228 is G and X417 is A.

In some embodiments, the transaminase polypeptide capable ofstereoselectively converting 1-phenylbutan-2-one, to the(S)-1-phenylbutan-2-amine comprises an amino acid sequence correspondingto SEQ ID NO: 22, 88, 90, 92, 106, 110, 138, 140, 142, 148, 150, 152,160, 164, 168, 170, 172, 178, 182, 188, or 190.

In some embodiments, the transaminase polypeptide is capable ofstereoselectively converting 1-phenylbutan-2-one, to(S)-1-phenylbutan-2-amine at a rate that is at least 5-fold or greaterthan the polypeptide of SEQ ID NO:2 and/or SEQ ID NO:18. In someembodiments, the transaminase polypeptide capable of stereoselectivelyconverting 1-phenylbutan-2-one to the (S)-1-phenylbutan-2-amine at arate at least 5 times greater than the polypeptide of SEQ ID NO:2 or SEQID NO:8 comprises an amino acid sequence corresponding to SEQ ID NO: 22,88, 90, 92, 106 or 110.

In some embodiments, the transaminase polypeptide described herein iscapable of stereoselectively converting the substrate3,3-dimethylbutan-2-one, to the product (S)-3,3-dimethylbutan-2-amine,as below:

at a rate that is greater than the polypeptide of SEQ ID NO:2 and/or SEQID NO:18. Residue positions associated with increase in activity onsubstrate 3,3-dimethylbutan-2-one include one or more of the following:X12, X30, X31, X44, X57, X81, X82, X85, X86, X95, X112, X113, X127,X153, X166, X181, X228, X233, X297, X311, X314, X317, X318, X319, X320,X321, X385, X407, X408, X409, X417, X434, and X438.

In some embodiments, the transaminase polypeptides capable of converting3,3-dimethylbutan-2-one, to the product (S)-3,3-dimethylbutan-2-amine ata rate that is greater than the polypeptide of SEQ ID NO:2 and/or SEQ IDNO:18 comprises an amino acid sequence having at least one of thefollowing features or set of features: X30 is A; X31 is A; X57 is L; X57is I; X82 is H; X85 is V; X85 is S; X85 is T; X85 is A; X85 is N; X85 isC; X86 is S; X86 is N; X86 is F; X153 is T; X153 is N; X153 is G; X153is S; X317 is M; X317 is Y; X319 is Q; X320 is A; X417 is A; X417 is I;X417 is C; X12 is G and X434 is V; X44 is A and X166 is S; X57 is I andX153 is S; X81 is D and X86 is H; X82 is H and X417 is F; X85 is S andX153 is A; X85 is A and X153 is A; X85 is A and X317 is L; X86 is H andX153 is A; X86 is S and X153 is S; X112 is I and X317 is L; X113 is Hand X407 is S; X153 is S and X233 is S; X311 is V and X314 is T; X314 isV and X409 is G; X318 is G and X408 is A; X57 is L, X417 is C and X438is L; X57 is F, X127 is L and X417 is C; X57 is S, X233 is L and X417 isV; X57 is A, X153 is S and X318 is G; X57 is F, X86 is H and X153 is Q;X57 is I, X86 is F and X320 is A; X57 is F, X86 is F and X153 is Q; X57is C, X86 is S and X417 is T; X57 is F, X318 is F and X417 is S; X57 isL, X86 is S and X153 is A; X57 is L, X86 is F and X318 is F; X57 is F,X318 is G and X417 is I; X86 is H, X153 is S and X417 is C; X86 is H,X153 is A and X417 is C; X86 is F, X153 is C and X297 is A; X86 is H,X233 is L and X417 is A; X86 is N, X228 is G and X317 is L; X95 is T,X153 is A, and X417 is C; X113 is C, X385 is R and X417 is C; X153 is A,X317 is L and X318 is G; X153 is A, X233 is T and X417 is C; X153 is C,X233 is L and X318 is R; X153 is T, X228 is G, and X321 is L; X153 is S,X317 is L, and X417 is C; X153 is T, X319 is V and X417 is I; X153 is S,X228 is G and X417 is V; X153 is C, X317 is Y, and X319 is Q; X153 is T,X228 is G and X417 is A; X233 is L, X321 is L and X417 is I; X228 is G,X318 is G and X417 is C; X317 is L, X318 is R and X417 is T; X86 is H,X153 is A, X228 is G and X417 is I; and X86 is H, X153 is S, X181 is Rand X417 is T.

In some embodiments, the transaminase polypeptide capable ofstereoselectively converting 3,3-dimethylbutan-2-one to(S)-3,3-dimethylbutan-2-amine comprises an amino acid sequencecorresponding to SEQ ID NO: 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40,42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 70, 72, 74, 76, 78,80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110,112, 114, 116, 118, 120, 134, 140, 142, 144, 146, 152, 154, 156, 158,162, 164, 168, 170, 172, 174, 176, 178, 180, 182, 184, 186, 188, 190, or192.

In some embodiments, the transaminase polypeptide is capable ofstereoselectively converting 3,3-dimethylbutan-2-one to(S)-3,3-dimethylbutan-2-amine, at a rate that is at least 1.1 fold orgreater than the polypeptide of SEQ ID NO:2 and/or SEQ ID NO:18. In someembodiments, the transaminase polypeptide capable of stereoselectivelyconverting 3,3-dimethylbutan-2-one to (S)-3,3-dimethylbutan-2-amine at arate that is at least 1.1 fold or greater than the polypeptide of SEQ IDNO:2 and/or SEQ ID NO:18 comprises an amino acid sequence correspondingto SEQ ID NO: 30, 34, 38, 44, 52, 54, 70, 72, 74, 76, 80, 82, 96, 98,100, 104, 118, 120, 164, 178, or 188.

In some embodiments, the transaminase polypeptide described herein iscapable of stereoselectively converting the substrate octan-2-one, tothe product (S)-octan-2-amine, as below:

at a rate that is greater than the polypeptide of SEQ ID NO:2 and/or SEQID NO:18. Residue positions associated with increase in activity onsubstrate octan-2-one include one or more of the following: X12, X30,X31, X44, X57, X81, X82, X85, X86, X95, X112, X113, X127, X153, X166,X181, X228, X233, X297, X311, X314, X317, X318, X319, X320, X321, X385,X407, X408, X409, X417, X434, and X438.

In some embodiments, the transaminase polypeptides capable of convertingoctan-2-one, to the product (S)-octan-2-amine comprises an amino acidsequence having at least one of the following features or set offeatures: X30 is A; X31 is A; X57 is I; X57 is L; X82 is H; X85 is V;X85 is S; X85 is T; X85 is A; X85 is N; X85 is C; X86 is S; X86 is N;X86 is F; X153 is S; X153 is T; X153 is N; X153 is G; X317 is M; X317 isY; X417 is A; X319 is Q; X320 is A; X417 is I; X417 is C; X12 is G andX434 is V; X44 is A and X166 is S; X57 is I and X153 is S; X81 is D andX86 is H; X82 is H and X417 is F; X85 is A and X317 is L; X85 is S andX153 is A; X85 is A and X153 is A; X86 is H and X153 is A; X86 is S andX153 is S; X112 is I and X317 is L; X113 is H and X407 is S; X153 is Sand X233 is S; X311 is V and X314 is T; X314 is V and X409 is G; X318 isG and X408 is A; X57 is L, X417 is C and X438 is L; X57 is F, X127 is Land X417 is C; X57 is S, X233 is L and X417 is V; X57 is S, X86 is G andX417 is C; X57 is A, X153 is S and X318 is G; X57 is F, X86 is H andX153 is Q; X57 is I, X86 is F and X320 is A; X57 is F, X86 is F and X153is Q; X57 is A, X153 is C and X321 is L; X57 is C, X86 is S and X417 isT; X57 is C, X86 is A and X317 is L; X57 is F, X318 is F and X417 is S;X57 is L, X86 is S and X153 is A; X57 is L, X86 is F and X318 is F; X57is F, X318 is G and X417 is I; X86 is F, X318 is R and X417 is A; X86 isF, X153 is C and X297 is A; X86 is S, X153 is T and X297 is A; X86 is H,X233 is L and X417 is A; X86 is N, X228 is G, and X317 is L; X86 is H,X153 is A and X417 is C; X86 is H, X153 is S and X417 is C; X95 is T,X153 is A and X417 is C; X113 is C, X385 is R and X417 is C; X153 is A,X233 is T and X417 is C; X153 is S, X318 is R and X417 is E; X153 is C,X233 is L and X318 is R; X153 is S, X228 is G and X417 is V; X153 is C,X317 is Y and X319 is Q; X153 is T, X228 is G, and X417 is A; X153 is T,X319 is V and X417 is I; X153 is T, X228 is G and X321 is L; X153 is S,X317 is L and X417 is C; X153 is A, X317 is L and X318 is G; X228 is G,X318 is G and X417 is C; X228 is G, X317 is L and X417 is C; X233 is L,X321 is L and X417 is I; X317 is L, X318 is R and X417 is T; X86 is H,X153 is A, X228 is G and X417 is I; and X86 is H, X153 is S, X181 is Rand X417 is T.

In some embodiments, the transaminase polypeptide capable ofstereoselectively converting octan-2-one to (S)-octan-2-amine comprisesan amino acid sequence corresponding to SEQ ID NO: 20, 22, 24, 26, 28,30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64,66, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100,102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 134, 136, 138, 140,142, 144, 146, 152, 154, 156, 158, 160, 162, 164, 166, 168, 170, 172,174, 178, 180, 182, 184, 186, 188, 190, or 192.

In some embodiments, the transaminase polypeptide is capable ofstereoselectively converting octan-2-one to (S)-octan-2-amine at a ratethat is at least 1.1 fold or greater than the polypeptide of SEQ ID NO:2and/or SEQ ID NO:18. In some embodiments, the transaminase polypeptidecapable of steroselectively converting octan-2-one to (S)-octan-2-amineat a rate that is at least 1.1 fold greater than the polypeptide of SEQID NO:2 and/or SEQ ID NO:18 comprises an amino acid sequencecorresponding to SEQ ID NO: 20, 22, 24, 26, 28, 30, 34, 38, 42, 44, 46,48, 52, 54, 70, 72, 74, 76, 80, 82, 84, 86, 92, 96, 98, 102, 104, 108,110, 112, 114, 116, 134, 136, 138, 140, 142, 144, 146, 152, 154, 156,164, 166, 168, 170, 172, 174, 178, 180, 182, 184, 188, 190, or 192.

In some embodiments, the transaminase polypeptide is capable ofstereoselectively converting octan-2-one to (S)-octan-2-amine at a ratethat is at least 5 fold or greater than the polypeptide of SEQ ID NO:2and/or SEQ ID NO:18. Exemplary polypeptides that are capable ofstereoselectively converting octan-2-one (S)-octan-2-amine at a ratethat is at least 5 fold greater than the polypeptide of SEQ ID NO:2and/or SEQ ID NO:18 comprises an amino acid sequence corresponding toSEQ ID NO: 22 or 192.

In some embodiments, the transaminase polypeptides described herein arecapable of stereoselectively converting the substrate1-(4-bromophenyl)ethanone, to the product(S)-1-(4-bromophenyl)ethanamine, as below

at a rate that is greater than the polypeptide of SEQ ID NO:2 and/or SEQID NO:18. Residue positions associated with increase in activity onsubstrate 1-(4-bromophenyl)ethanone include one or more of thefollowing: X12, X30, X31, X44, X57, X81, X82, X85, X86, X95, X112, X113,X127, X153, X153, X166, X181, X228, X233, X297, X311, X314, X317, X318,X319, X320, X321, X385, X407, X408, X409, X417, X434, and X438.

In some embodiments, the transaminase polypeptide capable ofstereoselectively converting 1-(4-bromophenyl)ethanone, to(S)-1-(4-bromophenyl)ethanamine comprises an amino acid sequence havingat least one of the following features or set of features: X30 is A; X57is L; X57 is I; X82 is H; X85 is V; X85 is T; X85 is A; X85 is N; X86 isN; X86 is F; X86 is S; X153 is S; X153 is T; X153 is N; X153 is G; X317is M; X317 is Y; X319 is Q; X320 is A; X417 is A; X417 is I; X417 is C;X12 is G and X434 is V; X44 is A and X166 is S; X57 is I and X153 is S;X81 is D and X86 is H; X82 is H and X417 is F; X85 is S and X153 is A;X85 is A and X153 is A; X86 is S and X153 is S; X86 is H and X153 is A;X112 is I and X317 is L; X113 is H and X407 is S; X153 is S and X233 isS; X314 is V and X409 is G; X318 is G and X408 is A; X31 is A, X311 is Vand X314 is T; X57 is L, X417 is C and X438 is L; X57 is F, X127 is Land X417 is C; X57 is I, X86 is F and X320 is A; X57 is S, X86 is G andX417 is C; X57 is C, X86 is S and X417 is T; X57 is C, X86 is A and X317is L; X57 is F, X318 is F and X417 is S; X57 is L, X86 is S and X153 isA; X57 is F, X318 is G and X417 is I; X86 is H, X153 is A and X417 is C;X86 is H, X153 is S and X417 is C; X86 is F, X318 is R and X417 is A;X86 is F, X153 is C and X297 is A; X86 is S, X153 is T and X297 I is A;X86 is N, X228 is G and X317 is L; X86 is H, X233 is L and X417 is A;X95 is T, X153 is A and X417 is C; X113 is C, X385 is R and X417 is C;X153 is A, X233 is T and X417 is C; X153 is A, X317 is L and X318 is G;X153 is 5, X318 is R and X417 is E; X153 is T, X228 is G and X321 is L;X153 is S, X317 is L and X417 is C; X153 is C, X233 is L and X318 is R;X153 is S, X228 is G and X417 is V; X153 is T, X319 is V and X417 is I;X153 is C, X317 is Y and X319 is Q; X153 is T, X228 is G and X417 is A;X228 is G, X317 is L and X417 is C; X228 is G, X318 is G and X417 is C;X233 is L, X321 is L and X417 is I; X317 is L, X318 is R and X417 is T;X86 is H, X153 is A, X228 is G and X417 is I; and X86 is H, X153 is S,X181 is R and X417 is T.

In some embodiments, the transaminase polypeptide capable of converting1-(4-bromophenyl)ethanone to (S)-1-(4-bromophenyl)ethanamine comprisesan amino acid sequence corresponding to SEQ ID NO: 20, 22, 24, 26, 28,30, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 60, 62, 64, 68, 70,72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104,106, 108, 110, 112, 114, 116, 118, 120, 136, 138, 144, 150, 152, 154,156, 158, 160, 162, 164, 166, 168, 170, 172, 174, 176, 178, 182, 184,186, 188, 190, or 192.

In some embodiments, the transaminase polypeptide is capable ofconverting 1-(4-bromophenyl)ethanone to (S)-1-(4-bromophenyl)ethanamineat a rate that is at least 1.1 fold or greater than the polypeptide ofSEQ ID NO:2 and/or SEQ ID NO:18. In some embodiments, the transaminasepolypeptide capable of converting 1-(4-bromophenyl)ethanone to(S)-1-(4-bromophenyl)ethanamine at a rate that is at least 1.1 fold orgreater than the polypeptide of SEQ ID NO:2 and/or SEQ ID NO:18comprises an amino acid sequence corresponding to SEQ ID NO: 20, 22, 24,26, 28, 34, 38, 42, 44, 46, 48, 50, 52, 54, 68, 70, 72, 74, 76, 78, 80,82, 84, 86, 88, 92, 94, 96, 98, 100, 102, 104, 108, 110, 112, 114, 116,118, 136, 150, 152, 154, 156, 160, 164, 166, 170, 172, 174, 182, 184,186, 188, or 192.

In some embodiments, the transaminase polypeptide is capable ofconverting 1-(4-bromophenyl)ethanone to the product(S)-1-(4-bromophenyl)ethanamine at a rate that is at least 5 fold orgreater than the polypeptide of SEQ ID NO:2 and/or SEQ ID NO:18. In someembodiments, the transaminase polypeptide capable of converting1-(4-bromophenyl)ethanone to (S)-1-(4-bromophenyl)ethanamine at a ratethat is at least 5-fold or greater than the polypeptide of SEQ ID NO:2and/or SEQ ID NO:18 comprises an amino acid sequence corresponding toSEQ ID NO: 84, 102, 108, 120, 122, 124, 128, 132, 172, 184, or 186.

In some embodiments, the transaminase polypeptide described herein arecapable of stereoselectively converting the substrate4-phenylbutan-2-one, to the product (R)-4-phenylbutan-2-amine, as below:

at a rate that is greater than the polypeptide of SEQ ID NO:2 and/or SEQID NO:18. Residue positions associated with increase in activity onsubstrate 4-phenylbutan-2-one include one or more of the following: X30,X31, X44, X57, X81, X82, X85, X86, X113, X153, X166, X181, X228, X233,X297, X317, X318, X319, X320, X321, X385, X407, X408, X417, and X438.

In some embodiments, the transaminase polypeptide capable ofstereoselectively converting 4-phenylbutan-2-one to(R)-4-phenylbutan-2-amine comprises an amino acid sequence having atleast one of the following features or set of features: X30 is A; X31 isA; X57 is L; X57 is I; X82 is H; X85 is V; X85 is S; X85 is T; X85 is A;X86 is S; X86 is N; X86 is F; X153 is S; X153 is T; X153 is N; X153 isG; X319 is Q; X317 is M; X317 is Y; X320 is A; X417 is A; X417 is I;X417 is C; X44 is A and X166 is S; X57 is I and X153 is S; X81 is D andX86 is H; X82 is H and X417 is F; X85 is A and X153 is A; X85 is A andX317 is L; X85 is S and X153 is A; X86 is S and X153 is S; X86 is H andX153 is A; X113 is H and X407 is S; X318 is G and X408 is A; X153 is Sand X233 is S; X57 is A, X153 is S and X318 is G; X57 is F, X86 is H andX153 is Q; X57 is I, X86 is F and X320 is A; X57 is F, X86 is F, andX153 is Q; X57 is A, X153 is C and X321 is L; X57 is L, X417 is C andX438 is L; X57 is S, X233 is L and X417 is V; X57 is C, X86 is S, andX417 is T; X57 is S, X86 is G and X417 is C; X57 is C; X86 is A and X317is L; X57 is F, X318 is F and X417 is S; X57 is L, X86 is S and X153 isA; X57 is L, X86 is F and X318 is F; X57 is F, X318 is G and X417 is I;X86 is H, X153 is S and X417 is C; X86 is H, X153 is A and X417 is C;X86 is F, X318 is R and X417 is A; X86 is F, X153 is C and X297 is A;X86 is S, X153 is T and X297 is A; X86 is H, X233 is L and X417 is A;X86 is N, X228 is G and X317 is L; X113 is C, X385 is R and X417 is C;X153 is A, X233 is T and X417 is C X153 is A, X317 is L and X318 is G;X153 is S, X318 is R and X417 is E; X153 is C, X233 is L and X318 is R;X153 is T, X228 is G and X321 is L; X153 is S, X317 is L and X417 is C;X153 is S, X228 is G and X417 is V; X153 is C, X317 is Y and X319 is Q;X153 is T, X228 is G and X417 is A; X228 is G, X317 is L and X417 is C;X228 is G, X318 is G and X417 is C; X233 is L, X321 is L and X417 is I;X317 is L, X318 is R and X417 is T; X86 is H, X153 is A, X228 is G andX417 is I; and X86 is H, X153 is S, X181 is R and X417 is T.

In some embodiments, the transaminase polypeptide capable ofstereoselectively converting 4-phenylbutan-2-one to(R)-4-phenylbutan-2-amine comprises an amino acid sequence correspondingto SEQ ID NO: 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46,48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82,84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114,116, 118, 134, 136, 138, 140, 142, 144, 146, 148, 150, 152, 154, 156,158, 160, 162, 164, 166, 168, 170, 172, 174, 178, 182, 184, 186, 188,190, or 192.

In some embodiments, the transaminase polypeptide is capable ofstereoselectively converting 4-phenylbutan-2-one to(R)-4-phenylbutan-2-amine at a rate that is at least 1.1 fold or greaterthan the polypeptide of SEQ ID NO:2 and/or SEQ ID NO:18. In someembodiments, the transaminase polypeptide capable of stereoselectivelyconverting 4-phenylbutan-2-one to (R)-4-phenylbutan-2-amine at a ratethat is at least 1.1 fold or greater than the polypeptide of SEQ ID NO:2and/or SEQ ID NO:18 comprises an amino acid sequence corresponding toSEQ ID NO: 20, 22, 24, 26, 28, 30, 34, 42, 44, 46, 52, 68, 72, 74, 76,78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 102, 104, 110, 112, 114,134, 136, 138, 140, 142, 144, 146, 148, 150, 154, 156, 158, 162, 164,166, 168, 172, 174, 178, 182, 184, 186, 188, 190, or 192.

In some embodiments, the transaminase polypeptide is capable ofstereoselectively converting 4-phenylbutan-2-one, to(R)-4-phenylbutan-2-amine at a rate that is at least 5-fold or greaterthan the polypeptide of SEQ ID NO:2 and/or SEQ ID NO:18. In someembodiments, the transaminase polypeptide capable of stereoselectivelyconverting 4-phenylbutan-2-one to (R)-4-phenylbutan-2-amine at a ratethat is at least 5-fold or greater than the polypeptide of SEQ ID NO:2and/or SEQ ID NO:18, comprises an amino acid sequence corresponding toSEQ ID NO: 154, 172, or 178.

In some embodiments, the transaminase polypeptides described herein arecapable of stereoselectively converting the substrate ethyl3-oxobutanoate, to the product (R)-ethyl 3-aminobutanoate, as below

at a rate that is greater than the polypeptide of SEQ ID NO:2 and/or SEQID NO:18. Residue positions associated with increase in activity onsubstrate ethyl 3-oxobutanoate include one or more of the following:X57, X85, X86, X147, X153, X233, X317, X318, and X417.

In some embodiments, the transaminase polypeptide capable ofstereoselectively converting ethyl 3-oxobutanoate to (R)-ethyl3-aminobutanoate comprises an amino acid sequence having at least one ofthe following features or set of features: X85 is V; X85 is S; X85 is T;X85 is A; X85 is N; X85 is C; X153 is T; X153 is N; X153 is G; X153 isS; X417 is C; X85 is S and X153 is A; X85 is A and X153 is A; X85 is Aand X317 is L; X86 is H and X153 is A; X85 is A, X153 is S and X417 isS; X85 is S, X153 is A and X233 is T; X85 is A, X147 is G and X153 is A;X86 is H, X153 is A and X417 is C; X86 is H, X153 is S and X417 is C;X153 is A, X317 is L and X318 is G; X57 is I, X85 is A, X86 is H andX417 is C; and X57 is L, X86 is F, X153 is S, X233 is T and X417 is T.

In some embodiments, the transaminase polypeptide capable ofstereoselectively converting ethyl 3-oxobutanoate to (R)-ethyl3-aminobutanoate comprises an amino acid sequence corresponding to SEQID NO: 32, 34, 36, 40, 44, 56, 58, 60, 62, 64, 66, 68, 70, 72, 86, 88,90, 92, 122, 126, 128, 130, or 132.

In some embodiments, the transaminase polypeptide is capable ofstereoselectively converting ethyl 3-oxobutanoate to (R)-ethyl3-aminobutanoate at a rate that is at least 5-fold or greater than thepolypeptide of SEQ ID NO:2 and/or SEQ ID NO:18. Polypeptides that arecapable of the above reaction include, but are not limited to, apolypeptide comprising an amino acid sequence corresponding to SEQ IDNO: 32, 36, 40, 56, 58, 60, 62, 64, 66, 126, 128, or 130.

In some embodiments, the transaminase polypeptides described herein arecapable of stereoselectively converting the substrate ethyl3-oxobutanoate, to the product (S)-ethyl 3-aminobutanoate, as below:

at a rate that is greater than the polypeptide of SEQ ID NO:2 and/or SEQID NO:18. Residue positions associated with increase in activity onsubstrate ethyl 3-oxobutanoate include one or more of the following:X12, X30, X31, X44, X57, X81, X82, X85, X86, X112, X113, X127, X153,X166, X228, X233, X297, X311, X314, X317, X318, X319, X320, X321, X385,X407, X408, X409, X417, X434, and X438.

In some embodiments, the transaminase polypeptide capable of convertingethyl 3-oxobutanoate to (S)-ethyl 3-aminobutanoate comprises an aminoacid sequence having at least one of the following features or set offeatures: X30 is A; X31 is A; X57 is I; X57 is L; X82 is H; X86 is S;X86 is N; X86 is F; X317 is M; X417 is A; X319 is Q; X320 is A; X12 is Gand X434 is V; X44 is A and X166 is S; X57 is I and X153 is S; X81 is Dand X86 is H; X82 is H and X417 is F; X85 is S and X153 is S; X86 is Sand X153 is S; X112 is I and X317 is L; X113 is H and X407 is S; X318 isG and X408 is A; X314 is V and X409 is G; X311 is V and X314 is T; X57is L, X417 is C and X438 is L; X57 is F, X127 is L and X417 is C; X57 isS, X233 is L and X417 is V; X57 is S, X86 is G and X417 is C; X57 is A,X153 is S and X318 is G; X57 is F, X86 is H and X153 is Q; X57 is I, X86is F and X320 is A; X57 is F, X86 is F and X153 is Q; X57 is A. X153 isC and X321 is L; X57 is C, X86 is A and X317 is L; X57 is F, X318 is Fand X417 is S; X57 is L, X86 is S and X153 is A; X57 is L, X86 is F andX318 is F; X57 is C, X86 is S and X417 is T; X57 is F, X318 is G andX417 is I; X86 is F, X318 is R and X417 is A; X86 is N, X228 is G andX317 is L; X86 is F, X153 is C and X297 is A; X86 is S, X153 is T andX297 is A; X86 is H, X233 is L and X417 is A; X113 is C, X385 is R andX417 is C; X153 is A, X233 is T and X417 is C; X153 is C, X233 is L andX318 is R; X153 is T, X228 is G and X321 is L; X153 is S, X317 is L andX417 is C; X153 is S, X228 is G and X417 is V; X153 is C, X317 is Y andX319 is Q; X153 is T, X228 is G and X417 is A; X228 is G, X317 is L andX417 is C; X228 is G, X318 is G and X417 is C; X233 is L, X321 is L andX417 is I; X317 is L, X318 is R and X417 is T; and X86 is H, X153 is A,X228 is G and X417 is I.

In some embodiments, the transaminase polypeptide capable ofstereoselectively converting ethyl 3-oxobutanoate to (S)-ethyl3-aminobutanoate comprises an amino acid sequence corresponding to SEQID NO: 20, 22, 24, 26, 28, 30, 38, 42, 46, 48, 50, 52, 54, 74, 78, 80,82, 94, 96, 98, 100, 102, 106, 112, 114, 116, 118, 120, 124, 134, 136,138, 140, 142, 144, 146, 148, 150, 152, 154, 156, 158, 162, 164, 166,168, 170, 172, 174, 178, 180, 182, 184, 186, 188, 190 or 192.

In some embodiments, the transaminase polypeptide is capable ofstereoselectively converting ethyl 3-oxobutanoate to (S)-ethyl3-aminobutanoate at a rate that is at least 1.1 fold or greater than thepolypeptide of SEQ ID NO:2 and/or SEQ ID NO:18. In some embodiments, thetransaminase polypeptide capable of converting ethyl 3-oxobutanoate to(S)-ethyl 3-aminobutanoate at a rate that is at least 1.1 fold orgreater than the polypeptide of SEQ ID NO:2 and/or SEQ ID NO:18comprises an amino acid sequence corresponding to SEQ ID NO: 22, 26, 28,38, 46, 56, 60, 64, 78, 84, 86, 90, 100, 102, 106, 112, 118, 136, 144,146, 154, 156, 158, 160, 164, 166, 168, 170, 172, 174, 178, 182, 188, or190.

In some embodiments, the transaminase polypeptide is capable ofstereoselectively converting ethyl 3-oxobutanoate to (S)-ethyl3-aminobutanoate at a rate that is at least 5-fold or greater than thepolypeptide of SEQ ID NO:2 and/or SEQ ID NO:18. In some embodiments, thetransaminase polypeptide capable of stereoselectively converting ethyl3-oxobutanoate to (S)-ethyl 3-aminobutanoate at a rate that is at least5-fold or greater than the polypeptide of SEQ ID NO:2 and/or SEQ IDNO:18 comprises an amino acid sequence corresponding to SEQ ID NO: 22,26, 28, 38, 46, 56, 60, 64, 78, 84, 86, 90, 100, 102, 106, 112, 118,136, 144, 154, 166, 170, 174, 178, or 188.

In some embodiments, the transaminase polypeptides described herein arecapable of stereoselectively converting the substrate1-(6-methoxynaphthalen-2-yl)ethanone, to the product(S)-1-(6-methoxynaphthalen-2-yl)ethanamine, as below:

at a rate that is greater than the polypeptide of SEQ ID NO:2 and/or SEQID NO:18. Residue positions associated with increase in activity onsubstrate 1-(6-methoxynaphthalen-2-yl)ethanone include one or more ofthe following: X57, X86, X153, X233, X317, X318, X320, X321, X417, andX438.

In some embodiments, the transaminase polypeptide capable of converting1-(6-methoxynaphthalen-2-yl)ethanone to(S)-1-(6-methoxynaphthalen-2-yl)ethanamine comprises an amino acidsequence having at least one of the following features or set offeatures: X57 is L; X86 is F or N; X417 is C, I or A; X57 is L, X86 isF, X153 is S, X233 is T and X417 is T; X57 is C, X86 is S and X417 is T;X57 is S, X233 is L, and X417 is V; X57 is A, X153 is S and X318 is G;X57 is A, X153 is C, and X321 is L; X57 is L, X86 is S, and X153 is A;X57 is S, X86 is G and X417 is C; X57 is L, X86 is F, X318 is F; X57 isF, X86 is F, and X153 is Q; X57 is I; X86 is F and X320 is A; X57 is C,X86 is A and X317 is L; X57 is L, X417 is C and X438 is L; X86 is F,X318 is R and X417 is A; X57 is F. X86 is H and X153 is Q; X57 is F,X318 is F and X417 is S; X86 is H, X153 is S, X181 is R and X417 is T;X153 is S, X317 is L and X417 is C; X153 is T, X228 is G and X417 is A;X57 is F, X127 is L and X417 is C; X228 is G, X317 is L and X417 is C;X233 is L, X321 is L and X417 is I; X228 is G, X318 is G and X417 is C;X86 is H, X153 is S and X417 is C; X86 is H, X233 is L and X417 is A;X86 is S and X153 is S; X86 is F, X153 is C and X297 is A; X153 is S,X228 is G and X417 is V; X57 is F, X318 is G and X417 is I; X153 is T,X228 is G and X321 is L; X317 is L, X318 is R and X417 is T; X153 is C,X317 is Y, and X319 is Q; X57 is I and X153 is S; X86 is H, X153 is Aand X417 is C; X153 is A, X233 is T and X417 is C; X95 is T, X153 is Aand X417 is C; X86 is N, X228 is G and X317 is L; and X86 is S, X153 isT, X297 is A.

In some embodiments, the transaminase polypeptide capable ofstereoselectively converting 1-(6-methoxynaphthalen-2-yl)ethanone to(S)-1-(6-methoxynaphthalen-2-yl)ethanamine comprises an amino acidsequence corresponding to SEQ ID NO: 24, 26, 28, 46, 48, 78, 84, 86, 88,92, 102, 108, 110, 114, 116, 126, 134, 136, 138, 140, 142, 144, 146,148, 150, 152, 154, 156, 158, 162, 166, 168, 170, 172, 174, 178, 180,182, 184, 186, 188, 190, or 192.

In some embodiments, the transaminase polypeptides described herein arecapable of steroselectively converting the substrate1-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)ethanone, to the product(S)-1-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)ethanamine, as below:

at a rate that is greater than the polypeptide of SEQ ID NO:2 and/or SEQID NO:18. Residue positions associated with increase in activity onsubstrate 1-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)ethanone include one ormore of the following: X57, X86, X153, X228, X233, X297, X318, X320,X417, and X438.

In some embodiments, the transaminase polypeptide capable of converting1-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)ethanone, to the product(S)-1-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)ethanamine comprises an aminoacid sequence having at least one of the following features or set offeatures: X31 is A; X57 is C, I or L; X86 is S or F; X153 is G or S;X417 is T or I; X57 is F, X86 is F, and X153 is Q; X57 is I and X153 isS; X57 is L, X86 is F, X153 is S, X233 is T and X417 is T; X86 is F,X153 is C, and X297 is A; X57 is L, X417 is C, and X438 is L; X57 is S,X233 is L, and X417 is V; X57 is L, X86 is S, X153 is A; X57 is S, X86is G, and X417 is C; X57 is A, X153 is S, X318 is G; X57 is I, X86 is Fand X320 is A; X57 is L, X86 is F, X318 is F; X153 is S, X228 is G, andX417 is V; X57 is C, X86 is A, and X317 is L; X153 is S and X233 is S;X57 is A, X153 is C and X321 is L; X86 is S and X153 is S; X86 is H,X153 is S, X181 is R, and X417 is T; X21 is N, X45 is N, X177 is V, X208is I, X211 is R, X324 is S, and X391 is T; X86 is H, X153 is A, X228 isG, and X417 is I; and X153 is C, X233 is L and X318 is R.

In some embodiments, the transaminase polypeptide capable ofstereoselectively converting1-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)ethanone, to the product(S)-1-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)ethanamine comprises an aminoacid sequence corresponding to SEQ ID NO: 16, 26, 28, 42, 44, 46, 48,72, 84, 98, 104, 106, 110, 114, 126, 134, 136, 140, 144, 146, 148, 152,156, 164, 166, 178, 180, or 182.

In some embodiments, the transaminase polypeptides described herein arecapable of stereoselectively converting the substrate1-(4-phenoxyphenyl)ethanone, to the product(S)-1-(4-phenoxyphenyl)ethanamine, as below:

at a rate that is greater than the polypeptide of SEQ ID NO:2 and/or SEQID NO:18. Residue positions associated with increase in activity onsubstrate 1-(4-phenoxyphenyl)ethanone include one or more of thefollowing: X57, X86, X153, X181, X233, X297, X318, X417, and X438.

In some embodiments, the transaminase polypeptide capable of converting1-(4-phenoxyphenyl)ethanone, to the product(S)-1-(4-phenoxyphenyl)ethanamine comprises an amino acid sequencehaving at least one of the following features or set of features: X31 isA; X86 is S or F; X57 is L or I; X153 is S or G; X417 is A or I; X57 isI and X153 is S; X86 is S and X153 is S; X153 is S and X233 is S; X86 isH and X153 is A; X86 is H; X153 is A and X417 is C; X95 is T, X153 is Aand X417 is C; X86 is H, X153 is S and X417 is C; X57 is L, X417 is Cand X438 is L; X57 is S, X233 is L and X417 is V; X57 is S, X86 is G andX417 is C; X57 is A, X153 is S, X318 is G; X57 is F, X86 is H and X153is Q; X57 is I, X86 is F and X320 is A; X57 is F, X86 is F and X153 isQ; X57 is C, X86 is S and X417 is T; X86 is F, X153 is C and X297 is A;X86 is H, X233 is L and X417 is A; X153 is C, X233 is L and X318 is R;X57 is C, X86 is A and X317 is L; X57 is L, X86 is S and X153 is A; X57is L, X86 is F and X318 is F; X153 is S, X228 is G and X417 is V; X153is T, X228 is G and X417 is A; X86 is H, X153 is A, X228 is G and X417is I; X86 is H, X153 is S, X181 is R, and X417 is T; and X57 is L, X86is F, X153 is S, X233 is T and X417 is T.

In some embodiments, the transaminase polypeptide capable ofstereoselectively converting 1-(4-phenoxyphenyl)ethanone to the product(S)-1-(4-phenoxyphenyl)ethanamine comprises an amino acid sequencecorresponding to SEQ ID NO: 16, 20, 26, 28, 42, 44, 46, 48, 72, 78, 84,88, 90, 92, 98, 104, 106, 108, 110, 114, 126, 134, 136, 140, 142, 144,146, 154, 156, 162, 164, 166, 178, 180, 182, or 190.

In some embodiments, the transaminase polypeptides described herein arecapable of stereoselectively converting the substrate(R)-4-oxotetrahydro-2H-pyran-3-yl-benzoate to the product(3S,4S)-3-aminotetrahydro-2H-pyran-3-yl benzoate, as below:

at a rate that is greater than the polypeptide of SEQ ID NO:2 and/or SEQID NO:18. Residue positions associated with increase in activity onsubstrate (R)-4-oxotetrahydro-2H-pyran-3-yl-benzoate include one or moreof the following: X57, X86, X153, X233, X317, X318, X320, X321, andX417.

In some embodiments, the transaminase polypeptide capable of converting(R)-4-oxotetrahydro-2H-pyran-3-yl-benzoate to the product(3S,4S)-3-aminotetrahydro-2H-pyran-3-yl benzoate comprises an amino acidsequence having at least one of the following features or set offeatures: X57 is I and X153 is S; X57 is A, X153 is S and X318 is G; X57is A, X153 is C and X321 is L; X57 is L, X86 is S and X153 is A; X57 isI, X86 is F, X320 is A; X57 is S, X86 is G, and X417 is C; X57 is C, X86is S and X417 is T; X57 is C, X86 is A and X317 is L; X57 is L, X86 isF, X153 is S. X233 is T and X417 is T.

In some embodiments, the transaminase polypeptide capable ofstereoselectively converting (R)-4-oxotetrahydro-2H-pyran-3-yl-benzoate,to the product (3S,4S)-3-benzyloxytetrahydro-2H-pyran-4-amine comprisesan amino acid sequence corresponding to SEQ ID NO: 46, 126, 136, 140,144, 148, 154, 166, or 178.

In some embodiments, the transaminase polypeptides described herein arecapable of stereoselectively converting the substrate(R)-3-(benzyloxy)dihydro-2H-pyran-4(3H)-one, to the product(3S,4S)-3-(benzyloxy)tetrahydro-2H-pyran-4-amine, as below:

at a rate that is greater than the polypeptide of SEQ ID NO:2 and/or SEQID NO:18. Residue positions associated with increase in activity onsubstrate (R)-3-(benzyloxy)dihydro-2H-pyran-4(3H)-one include one ormore of the following: X57, X86, X153, X233, X317, X318, X320, X321, andX417.

In some embodiments, the transaminase polypeptide capable of converting(R)-3-(benzyloxy)dihydro-2H-pyran-4(3H)-one, to(3S,4S)-3-(benzyloxy)tetrahydro-2H-pyran-4-amine comprises an amino acidsequence having at least one of the following features or set offeatures: X30 is A; X31 is A; X57 is I or L; X82 is H; X85 is S, T, A;X86 is S, F; X153 is N, G, S, T; X317 is M or Y; X319 is Q; X320 is A;X417 is A, I or C; X57 is I and X153 is S; X85 is S and X153 is S; X81is D and X86 is H; X86 is H and X153 is A; X86 is S and X153 is S; X85is S and X153 is A; X85 is A and X153 is A; X314 is V and X409 is G;X311 is V and X314 is T; X82 is H and X417 is F; X85 is A and X317 is L;X318 is G and X408 is A; X153 is S and X233 is S; X113 is H and X407 isS; X12 is G and X434 is V; X112 is I and X317 is L; X44 is A and X166 isS; X86 is H, X153 is S and X417 is C; X57 is F. X127 is L and X417 is C;X57 is S, X86 is G and X417 is C; X228 is G, X317 is L, X417 is C; X57is F, X86 is H and X153 is Q; X86 is F, X318 is R and X417 is A; X86 isF, X153 is C and X297 is A; X86 is N, X228 is G and X317 is L; X57 is L,X86 is F and X318 is F; X153 is S, X228 is G and X417 is V; X57 is F,X86 is F and X153 is Q; X57 is L, X417 is C and X438 is L; X57 is A,X153 is C and X321 is L; X57 is S, X233 is L and X417 is V; X86 is S,X153 is T and X297 is A; X57 is F, X318 is F and X417 is S; X153 is T,X319 is V and X417 is I; X57 is S, X233 is L and X417 is V; X57 is I,X86 is F and X320 is A; X57 is F, X318 is G and X417 is I; X153 is C,X317 is Y and X319 is Q; X57 is L, X86 is S and X153 is A; X233 is L,X321 is L and X417 is I; X95 is T, X153 is A; and X417 is C; X86 is H,X153 is A and X417 is C; X228 is G, X318 is G and X417 is C; X85 is S,X153 is A and X233 is T; X57 is A, X153 is S and X318 is G; X153 is S,X318 is R and X417 is E; X153 is C, X233 is L and X318 is R; X153 is A;X233 is T and X417 is C; X85 is A, X147 is G and X153 is A; X153 is S,X317 is L and X417 is C; X317 is L, X318 is R and X417 is T; X153 is T,X228 is G and X417 is A; X57 is C, X86 is A and X317 is L; X153 is A,X317 is L and X318 is G; X57 is C, X86 is S and X417 is T; X86 is H,X233 is L and X417 is A; X153 is T, X228 is G, X321 is L; X113 is C,X385 is R and X417 is C; X86 is H, X153 is S, X181 is R and X417 is T;X86 is H, X153 is A, X228 is G and X417 is I; X57 is I, X85 is A, X86 isH and X417 is C; and X57 is L, X86 is F, X153 is S, X233 is T and X417is T.

In some embodiments, the transaminase polypeptide capable ofstereoselectively converting(R)-3-(benzyloxy)dihydro-2H-pyran-4(31^(˜)1)-one to(3S,4S)-3-(benzyloxy)tetrahydro-2H-pyran-4-amine comprises an amino acidsequence corresponding to SEQ ID NO: 20, 22, 26, 28, 30, 32, 34, 36, 40,42, 44, 46, 48, 50, 52, 58, 60, 68, 70, 72, 78, 82, 84, 86, 88, 90, 92,94, 96, 98, 100, 102, 104, 106, 108, 110, 114, 116, 118, 122, 126, 128,130, 132, 134, 136, 138, 140, 142, 144, 146, 148, 150, 152, 154, 156,158, 160, 162, 164, 166, 168, 170, 172; 174, 176, 178, 180, 182, 184,186, 188, 190, or 192.

In some embodiments, the expression of the transaminase polypeptides ofthe invention are improved as compared to the expression of thepolypeptide of SEQ ID NO:2 encoded by the polynucleotide of SEQ ID NO:1in a host cell, particularly an E. coli host cell. In such embodiments,the transaminase polypeptide can have a amino acid sequence having atleast one or more of the following features: X4 is R; X6 is R or I or N;X9 is T or G; X6 is R and X133 is T; X12 is K and X302 is K; and X9 isT, X86 is Y and X294 is V. In some embodiments, the transaminasepolypeptide with increased expression can be encoded by a polynucleotidesequence having one or more of the following residue differences ascompared to the polynucleotide sequence of SEQ ID NO:1 or SEQ ID NO:17:X852 is T and X861 is A; X18 is T and X286 is T; X891 is C; X12 is A andX15 is A and X18 is T; X309 is T; and X561 is C.

Exemplary transaminase polypeptides that are capable of increasedexpression include, but are not limited to, polypeptides comprising anamino acid sequence corresponding to SEQ ID NO: 4, 6, 8, 12, 14, 194,196, or 198.

Because the reference polypeptide having the amino acid sequence of SEQID NO:18 is capable of converting the substrate to the product at a rate(for example, 100% conversion in 20 hours of 1 g/L substrate with about10 g/L of the transaminase, in 50% isopropylamine at pH 8) and with astereoselectivity that is improved over wild-type (SEQ ID NO:2), thepolypeptides herein that are improved over SEQ ID NO:18 are alsoimproved over wild-type.

Table 2 below provides a list of SEQ ID NOs having increased thermo-and/or solvent stability as compared to the wildtype transaminase of SEQID NO:2. All sequences are derived from the wild-type Vibrio fluvialistransaminase sequence (SEQ ID NO:2). In Table 2 below, each row liststwo SEQ ID NOs, where the odd numbers in the column labeled “Nuc ID”refer to the nucleotide sequence that codes for the amino acid sequenceprovided by the even numbers in the column labeled “Pep ID”. The aminoacid substitutions as compared to the thermostable Vibrio fluvialisamino acid sequence of SEQ ID NO:2 are listed in the column “ActiveAmino Acid Mutations.”

TABLE 2 List of Sequences and Corresponding Thermostability ImprovementsActive Amino Acid Mutations % Residual % Activity at Nuc Pep (ascompared to Activity 50° C. rel. to ID ID SEQ ID NO: 2) 50° C. 23 h^(a)35° C., 23 h^(b) 1 2 — ND¹ ND¹ 9 10 A9T; S398R; S420N 6.0 ND¹ 11 12 A9T;F86Y; M294V 4.6 0 15 16 A9T; D21N; F86Y; T208I; 18% M294V 17 18 A9T;N45H; F86Y; V177L; 53% R211K; M294V; S324G; T391A ¹ND = not detectable^(a)% activity measured as % conversion at 50° C. of 1.0M pyruvate with1.0M isopropylamine at pH 9. ^(b)% activity measured as % conversion ofpyruvate after 23 h at 50° C. compared to same reaction at 35° C.

Table 3 below provides a list of SEQ ID NOs with their associatedactivities of transaminases for converting seven different aminoacceptor substrates to the corresponding S-enantiomers of the aminoproducts. Substrates Ito 7 are (Sub 1) 3,4-dihydronaphthalen-1(2H)-one;(Sub 2) 1-phenylbutan-2-one; (Sub 3) 3,3-dimethylbutan-2-one; (Sub 4)octan-2-one; (Sub 5) ethyl 3-oxobutanoate; (Sub 6) 4-phenylbutan-2-one;and (Sub 7) 1-(4-bromophenyl)ethanone. The amino acid substitutions ascompared to the thermostable Vibrio fluvialis amino acid sequence of SEQID NO:18 are listed in the column “Active Amino Acid Mutations.” In theactivity columns, one or more plus “+” signs indicate polypeptideshaving an improved ability to convert the amino acceptor substrate tothe chiral amine product as compared to the wild-type amino acidsequence of SEQ ID NO:2. Two plus signs “++” indicates that thepolypeptide is about 1.1 to 5-fold improved as compared to SEQ ID NO:18.Three plus signs “+++” indicates that the polypeptide is about 5 to10-fold improved as compared to SEQ ID NO:18. Four plus signs “++++”indicates that the polypeptide is more than 10-fold improved as comparedto SEQ ID NO:18. A blank indicates that data are unavailable. Substrates3-7 show increased activity with most of the mutated polypeptides.Substrates 1 and 2 show increased activity with fewer polypeptides.

TABLE 3 List of Sequences and Corresponding Activity Improvement Nuc PepActive Amino Acid Sub Sub Sub Sub Sub Sub Sub ID ID Mutations 1 2 3 4 56 7 19 20 Y86S + ++ ++ ++ ++ 21 22 G81D; Y86H ++++ + +++ + ++ ++ 23 24Y86N + ++ ++ ++ ++ 25 26 Y86F + ++ + ++ ++ 27 28 W57L + ++ + ++ ++ 29 30Y82H; L417F ++ ++ ++ ++ + 31 32 F85A; F317L; + + + + 33 34 V153A; F317L;P318G ++ ++ ++ ++ ++ 35 36 F85S; V153A + + + + + 37 38 Y113H; C407S + ++++ + + ++ 39 40 F85A; V153A + + + + + 41 42 W57I + + ++ + ++ ++ 43 44V153S ++ ++ ++ ++ ++ ++ 45 46 W57I; V153S + ++ + ++ ++ 47 48 Y86S;V153S + ++ ++ + ++ 49 50 P318G; T408A + + ++ + ++ 51 52 Y82H + ++ ++ ++++ ++ 53 54 E12G; M434V ++ ++ ++ + ++ 55 56 F85V + + + + + + 57 58F85S + + + + 59 60 F85T + + + + + 61 62 F85A + + + + + 63 64F85N + + + + 65 66 F85C + + + + 67 68 V153T + ++ ++ ++ ++ ++ 69 70 V153N++ ++ ++ + ++ 71 72 V153G ++ ++ ++ ++ ++ 73 74 F317M + ++ ++ ++ ++ ++ 7576 F317Y + ++ ++ ++ ++ ++ 77 78 L417A + + + + ++ ++ 79 80 H319Q + ++ ++++ ++ ++ 81 82 G320A + ++ ++ ++ ++ ++ 83 84 L417I + + ++ + ++ +++ 85 86L417C + ++ + ++ ++ 87 88 Y86H; V153A; L417C +++ + + ++ ++ ++ 89 90 Y86H;V153A +++ + + + ++ + 91 92 Y86H; V153S; L417C +++ + ++ ++ ++ ++ 93 94T30A + + + ++ ++ ++ 95 96 V44A; N166S + ++ ++ ++ ++ ++ 97 98 V31A + ++++ ++ ++ ++ 99 100 I314V; D409G + ++ + + + ++ 101 102 V153A; P233T;L417C + ++ + ++ +++ 103 104 V153S; P233S ++ ++ ++ ++ ++ ++ 105 106 Y86H;V153A; A228G; L417I +++ + + + + + 107 108 M95T; V153A; L417C + ++ ++ ++++ 109 110 Y86H; V153S; C181R; L417T +++ + ++ ++ ++ ++ 111 112 Y113C;K385R; L417C + ++ + ++ ++ 113 114 W57L; L417C; F438L + ++ + ++ ++ 115116 W57F; M127L; L417C + ++ + + ++ 117 118 I311V; 1314T + ++ + + + ++119 120 F112I; F317L ++ + ++ + 133 134 W57S; P233L; L417V + ++ + ++ 135136 W57S; Y86G; L417C ++ + ++ ++ 137 138 A228G; F317L; L417C + ++ ++++ + 139 140 W57A; V153S; P318G + + ++ ++ ++ 141 142 W57F; Y86H; V153Q++ + ++ ++ ++ 143 144 W57I; Y86F; G320A + ++ + ++ + 145 146 W57F; Y86F;V153Q + ++ +++ ++ 147 148 W57A; V153C; F321L + ++ ++ ++ 149 150 Y86F;P318R; L417A + + ++ ++ ++ 151 152 A228G; P318G; L417C + + ++ ++ + ++ 153154 W57C; Y86S; L417T + ++ + +++ ++ 155 156 Y86F; V153C; V297A + ++ +++++ ++ 157 158 Y86S; V153T; V297A + + +++ ++ + 159 160 V153S; P318R;L417E + + + +++ + ++ 161 162 Y86H; P233L; L417A + + ++ ++ + 163 164V153C; P233L; P318R ++++ + ++ ++ +++ ++ ++ 165 166 W57C; Y86A; F317L++ + ++ ++ 167 168 Y86N; A228G; F317L + + ++ +++ ++ + 169 170 V153T;A228G; F321L ++ + ++ ++++ + ++ 171 172 V153S; F317L; L417C ++ ++ + +++++ +++ +++ 173 174 W57F; P318F; L417S + ++ + ++ ++ 175 176 V153T;H319V; L417I + ++ + + 177 178 W57L; Y86S; V153A + ++ ++ + +++ + 179 180W57L; Y86F; P318F + ++ ++ ++ 181 182 V153S; A228G; L417V; ++ + ++ +++ ++++ 183 184 P233L; F321L; L417I ++ + ++ ++ ++ +++ 185 186 F317L; P318R;L417T + + ++ ++ +++ 187 188 V153C; F317Y; H319Q +++ + ++ ++ ++++ ++ ++189 190 V153T; A228G; L417A ++ + ++ +++ ++ + 191 192 W57F; P318G;L417I + +++ ++ ++ ++

Table 4 below provides a list of SEQ ID NOs with their associatedactivities for converting two different amino acceptor substrates to thecorresponding R-enantiomers of the amino products. Substrates 5 and 6are (Sub 5) ethyl 3-oxobutanoate and (Sub 6) 4-phenylbutan-2-one. Allsequences below are derived from the wild-type Vibrio fluvialistransaminase sequence (SEQ ID NO:2). In Table 4 below, the odd numberedSED ID NOs in the column labeled “Nuc ID” refer to the nucleotidesequence that codes for the amino acid sequence provided by the evennumbered SEQ ID NOs in the column labeled “Pep ID”. The amino acidsubstitutions as compared to the amino acid sequence of SEQ ID NO:18 arelisted in the column “Active Amino Acid Mutations.” In the activitycolumns, one or more plus “+” signs indicate polypeptides having animproved ability to convert the amino acceptor substrate to the chiralamine product as compared to the wild-type amino acid sequence of SEQ IDNO:2. Two plus signs “++” indicates that the polypeptide is about 1.1 to5-fold improved as compared to SEQ ID NO:18. Three plus signs “+++”indicates that the polypeptide is about 5 to 10-fold improved ascompared to SEQ ID NO:18. Four plus signs “++++” indicates that thepolypeptide is more than 10-fold improved as compared to SEQ ID NO:18. Ablank indicates that data are unavailable. Substrate 5 shows increasedactivity with most of the mutated polypeptides. Substrate 6 showsincreased activity with fewer polypeptides.

TABLE 4 List of Sequences and Corresponding Activity Improvement Nuc PepActive Amino Acid Mutations ID ID (as compared to SEQ ID NO: 18) Sub 5Sub 6 21 22 G81D; Y86H + 29 30 Y82H; L417F + 31 32 F85A; F317L ++++ 3334 V153A; F317L; P318G ++ 35 36 F85S; V153A ++++ 39 40 F85A; V153A ++++43 44 V153S ++ 47 48 Y86S; V153S ++ 55 56 F85V ++++ 57 58 F85S ++++ 5960 F85T ++++ 61 62 F85A ++++ 63 64 F85N ++++ 65 66 F85C ++++ 67 68 V153T++ 69 70 V153N ++ 71 72 V153G ++ 75 76 F317Y ++ 83 84 L417I + 85 86L417C + 87 88 Y86H; V153A; L417C ++ 89 90 Y86H; V153A + 91 92 Y86H;V153S; L417C ++ 103 104 V153S; P233S ++ 107 108 M95T; V153A; L417C + 109110 Y86H; V153S; C181R; L417T ++ 119 120 F112I; F317L + 121 122 F85A;W147G; V153A ++ ++++ 123 124 F85S; V153S ++++ 125 126 W57L; Y86F; V153S;P233T; L417T +++ 127 128 F85S; V153A; P233T +++ ++++ 129 130 W57I; F85A;Y86H; L417C +++ 131 132 F85A; V153S; L417S ++ ++++ 159 160 V153S; P318R;L417E ++ 175 176 V153T; H319V; L417I ++

In some embodiments, an improved transaminase comprises an amino acidsequence that is at least about 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%,92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to SEQ ID NO:2 orSEQ ID NO:18, wherein the amino acid sequence comprises any one of theset of mutations contained in any one of the polypeptide sequenceslisted in Table 3 or Table 4 as compared to a reference sequencecorresponding to SEQ ID NO:2 or SEQ ID NO:18. In some embodiments, thistransaminase polypeptide comprises any one of the set of mutationslisted in Table 3 or Table 4. In some embodiments, the engineeredtransaminases can have additionally about 1-2, 1-3, 1-4, 1-5, 1-6, 1-7,1-8, 1-9, 1-10, 1-15, 1-20, 1-21, 1-22, 1-23, 1-24, 1-25, 1-30, 1-35,1-40, 1-45, 1-50, 1-55, or 1-60 residue differences at other residuepositions. In some embodiments, the number of differences as compared tothe reference sequence can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 16, 17,18, 19, 20, 21, 22, 23, 24, 25, 30, 30, 35, 40, 45, 50, 55, or 60residue positions. In some embodiments, the residue differences compriseconservative mutations.

In some embodiments, an improved transaminase polypeptide comprises anamino acid sequence that is at least about 80%, 85%, 86%, 87%, 88%, 89%,90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to areference sequence corresponding to SEQ ID NO: 4, 6, 8, 10, 16, 18, 20,22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56,58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88. 90, 92,94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 122,124, 126, 128, 130, 132, 134, 136, 138, 140, 142, 144, 146, 148, 150,152, 154, 156, 158, 160, 162, 164, 166, 168, 170. 172, 174, 176, 178,180, 182, 184, 186, 188, 190, 192, 194, 196, or 198, wherein theengineered transaminase amino acid sequence comprises any one of the setof mutations contained in any one of the polypeptide sequences listed inTable 3 or Table 4 as compared to a reference sequence corresponding toSEQ ID NO:2 or SEQ ID NO:18. In some embodiments, this transaminasepolypeptide comprises any one of the set of mutations listed in Table 3or Table 4. In some embodiments, these engineered transaminases can haveadditionally about 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-15,1-20, 1-21, 1-22, 1-23, 1-24, 1-25, 1-30, 1-35, 1-40, 1-45, 1-50, 1-55,or 1-60 residue differences at other residue positions. In someembodiments, the number of differences as compared to the referencesequence can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 16, 17, 18, 19, 20,21, 22, 23, 24, 25, 30, 30, 35, 40, 45, 50, 55, or 60 residue positions.In some embodiments, the residue differences comprise conservativemutations.

In some embodiments, the amino acid sequences of the polypeptides of thecurrent invention specifically exclude those that differ from thewild-type sequence of Vibrio fluvialis by only one of any of thefollowing single mutations: residue X57 is G; residue X147 is G; residueX231 is G; residue X233 is L; residue X265 is L; residue X285 is A;residue X297 is A; and residue X415 is L.

The engineered transaminase enzymes described herein can be obtained bymutagenizing a gene encoding a naturally-occurring wild-typetransaminase enzyme that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identical to the amino acid sequence of Vibrio fluvialis transaminase(SEQ ID NO:2) utilizing standard laboratory techniques, includingvarious mutagenesis and recombination techniques.

As will be appreciated by those of skill in the art, some of theabove-defined categories of amino acid residues used to describe theengineered transaminases herein, unless otherwise specified, are notmutually exclusive. Thus, amino acids having side chains exhibiting twoor more physico-chemical properties can be included in multiplecategories. The appropriate classification of any amino acid or residuewill be apparent to those of skill in the art, especially in light ofthe detailed disclosure provided herein.

In some embodiments, the improved engineered transaminase polypeptidescomprise deletions of the engineered transaminase polypeptides describedherein. Thus, for each and every embodiment of the transaminasepolypeptides of the disclosure, the deletions can comprise one or moreamino acids, 2 or more amino acids, 3 or more amino acids, 4 or moreamino acids, 5 or more amino acids, 6 or more amino acids, 8 or moreamino acids, 10 or more amino acids, 15 or more amino acids, or 20 ormore amino acids, up to 10% of the total number of amino acids, up to10% of the total number of amino acids, up to 20% of the total number ofamino acids, or up to 30% of the total number of amino acids of thetransaminase polypeptides, as long as the functional activity and/orimproved properties of the transaminase is maintained. In someembodiments, the deletions can comprise, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7,1-8, 1-9, 1-10, 1-15, 1-20, 1-21, 1-22, 1-23, 1-24, 1-25, 1-30, 1-35,1-40, 1-45, 1-50, 1-55, or 1-60 amino acid residues. In someembodiments, the number of deletions can be 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 30, 30, 35, 40, 45, 50,55, or 60 amino acids. In some embodiments, the deletions can comprisedeletions of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 18,20, 21, 22, 23, 24, 25 or 30 amino acid residues.

In some embodiments, the improved engineered transaminase polypeptidescan comprise fragments of the engineered transaminase enzymes describedherein. In some embodiments, the polypeptide fragments can be 70%, 80%,90%, 95%, 98%, or 99% of the full-length transaminase polypeptide, suchas the transaminase of SEQ ID NO:18.

The polypeptides described herein are not restricted to the geneticallyencoded amino acids. In addition to the genetically encoded amino acids,the polypeptides described herein may be comprised, either in whole orin part, of naturally-occurring and/or synthetic non-encoded aminoacids. Certain commonly encountered non-encoded amino acids of which thepolypeptides described herein may be comprised include, but are notlimited to: the D-stereomers of the genetically-encoded amino acids;2,3-diaminopropionic acid (Dpr); α-aminoisobutyric acid (Aib);ε-aminohexanoic acid (Aha); δ-aminovaleric acid (Ava); N-methylglycineor sarcosine (MeGly or Sar); ornithine (Orn); citrulline (Cit);t-butylalanine (Bua); t-butylglycine (Bug); N-methylisoleucine (MeIle);phenylglycine (Phg); cyclohexylalanine (Cha); norleucine (Nle);naphthylalanine (NaI); 2-chlorophenylalanine (Ocf);3-chlorophenylalanine (Mcf); 4-chlorophenylalanine (Pcf);2-fluorophenylalanine (Off); 3-fluorophenylalanine (Mff);4-fluorophenylalanine (Pff); 2-bromophenylalanine (Obf);3-bromophenylalanine (Mbf); 4-bromophenylalanine (Pbf);2-methylphenylalanine (Omf); 3-methylphenylalanine (Mmf);4-methylphenylalanine (Pmf); 2-nitrophenylalanine (Onf);3-nitrophenylalanine (Mnf); 4-nitrophenylalanine (Pnf);2-cyanophenylalanine (Ocf); 3-cyanophenylalanine (Mcf);4-cyanophenylalanine (Pcf); 2-trifluoromethylphenylalanine (Otf);3-trifluoromethylphenylalanine (Mtf); 4-trifluoromethylphenylalanine(Ptf); 4-aminophenylalanine (Paf); 4-iodophenylalanine (Pif);4-aminomethylphenylalanine (Pamf); 2,4-dichlorophenylalanine (Opef);3,4-dichlorophenylalanine (Mpcf); 2,4-difluorophenylalanine (Opff);3,4-difluorophenylalanine (Mpff); pyrid-2-ylalanine (2pAla);pyrid-3-ylalanine (3pAla); pyrid-4-ylalanine (4pAla); naphth-1-ylalanine(1nAla); naphth-2-ylalanine (2nAla); thiazolylalanine (taAla);benzothienylalanine (bAla); thienylalanine (tAla); furylalanine (fAla);homophenylalanine (hPhe); homotyrosine (hTyr); homotryptophan (hTrp);pentafluorophenylalanine (5ff); styrylkalanine (sAla); authrylalanine(aAla); 3,3-diphenylalanine (Dfa); 3-amino-5-phenypentanoic acid (Afp);penicillamine (Pen); 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid(Tic); β-2-thienylalanine (Thi); methionine sulfoxide (Mso);N(w)-nitroarginine (nArg); homolysine (hLys);phosphonomethylphenylalanine (pmPhe); phosphoserine (pSer);phosphothreonine (pThr); homoaspartic acid (hAsp); homoglutanic acid(hGlu); 1-aminocyclopent-(2 or 3)-ene-4 carboxylic acid; pipecolic acid(PA), azetidine-3-carboxylic acid (ACA);1-aminocyclopentane-3-carboxylic acid; allylglycine (aOly);propargylglycine (pgGly); homoalanine (hAla); norvaline (nVal);homoleucine (hLeu), homovaline (hVal); homoisolencine (hIle);homoarginine (hArg); N-acetyl lysine (AcLys); 2,4-diaminobutyric acid(Dbu); 2,3-diaminobutyric acid (Dab); N-methylvaline (MeVal);homocysteine (hCys); homoserine (hSer); hydroxyproline (Hyp) andhomoproline (hPro). Additional non-encoded amino acids of which thepolypeptides described herein may be comprised will be apparent to thoseof skill in the art (see, e.g., the various amino acids provided inFasman, 1989, CRC Practical Handbook of Biochemistry and MolecularBiology, CRC Press, Boca Raton, Fla., at pp. 3-70 and the referencescited therein, all of which are incorporated by reference). These aminoacids may be in either the L- or D-configuration.

Those of skill in the art will recognize that amino acids or residuesbearing side chain protecting groups may also comprise the polypeptidesdescribed herein. Non-limiting examples of such protected amino acids,which in this case belong to the aromatic category, include (protectinggroups listed in parentheses), but are not limited to: Arg(tos),Cys(methylbenzyl), Cys (nitropyridinesulfenyl), Glu(δ-benzylester),Gln(xanthyl), Asn(N-δ-xanthyl), His(bom), His(benzyl), His(tos),Lys(fmoc), Lys(tos), Ser(O-benzyl), Thr (O-benzyl) and Tyr(O-benzyl).

Non-encoding amino acids that are conformationally constrained of whichthe polypeptides described herein may be composed include, but are notlimited to, N-methyl amino acids (L-configuration); 1-aminocyclopent-(2or 3)-ene-4-carboxylic acid; pipecolic acid; azetidine-3-carboxylicacid; homoproline (hPro); and 1-aminocyclopentane-3-carboxylic acid.

As described above the various modifications introduced into thenaturally occurring polypeptide to generate an engineered transaminaseenzyme can be targeted to a specific property of the enzyme.

In some embodiments, the polypeptides of the disclosure can be in theform of fusion polypeptides in which the engineered polypeptides arefused to other polypeptides, such as, by way of example and notlimitation, antibody tags (e.g., myc epitope), purification sequences(e.g., His tags for binding to metals), and cell localization signals(e.g., secretion signals). Thus, the engineered polypeptides describedherein can be used with or without fusions to other polypeptides.

In some embodiments, the polypeptide described herein can be provided inthe form of kits. The enzymes in the kits may be present individually oras a plurality of enzymes. The kits can further include reagents forcarrying out the enzymatic reactions, substrates for assessing theactivity of enzymes, as well as reagents for detecting the products. Thekits can also include reagent dispensers and instructions for use of thekits.

In some embodiments, the polypeptides can be provided on a physicalsubstrate. In some embodiments, the polypeptides can be provided in theform of an array in which the polypeptides are arranged in positionallydistinct locations. The array can be used to test a variety of substratecompounds for conversion by the polypeptides. “Substrate,” “support,”“solid support,” “solid carrier,” or “resin” in the context of arraysrefer to any solid phase material. Substrate also encompasses terms suchas “solid phase,” “surface,” and/or “membrane.” A solid support can becomposed of organic polymers such as polystyrene, polyethylene,polypropylene, polyfluoroethylene, polyethyleneoxy, and polyacrylamide,as well as co-polymers and grafts thereof A solid support can also beinorganic, such as glass, silica, controlled pore glass (CPG), reversephase silica or metal, such as gold or platinum. The configuration of asubstrate can be in the form of beads, spheres, particles, granules, agel, a membrane or a surface. Surfaces can be planar, substantiallyplanar, or non-planar. Solid supports can be porous or non-porous, andcan have swelling or non-swelling characteristics. A solid support canbe configured in the form of a well, depression, or other container,vessel, feature, or location. A plurality of supports can be configuredon an array at various locations, addressable for robotic delivery ofreagents, or by detection methods and/or instruments.

In certain embodiments, the kits of the present disclosure includearrays comprising a plurality of different transaminase polypeptides atdifferent addressable position, wherein the different polypeptides aredifferent variants of a reference sequence each having at least onedifferent improved enzyme property. Such arrays comprising a pluralityof engineered polypeptides and methods of their use are described in,e.g., WO2009/008908A2.

In some embodiments, the transaminase polypeptides can be bound on aphysical substrate. The transaminase polypeptide can be boundnon-covalently or covalently. Various methods for conjugation tosubstrates, e.g., membranes, beads, glass, etc. are described in, amongothers, Hermanson, G.T., Bioconjugate Techniques, Second Edition,Academic Press; (2008), and Bioconjugation Protocols: Strategies andMethods, In Methods in Molecular Biology, C. M. Niemeyer ed., HumanaPress (2004); the disclosures of which are incorporated herein byreference.

6.4 Polynucleotides Encoding Engineered Transaminases

In another aspect, the present disclosure provides polynucleotidesencoding the engineered transaminase enzymes. The polynucleotides may beoperatively linked to one or more heterologous regulatory sequences thatcontrol gene expression to create a recombinant polynucleotide capableof expressing the polypeptide. Expression constructs containing aheterologous polynucleotide encoding the engineered transaminase can beintroduced into appropriate host cells to express the correspondingtransaminase polypeptide.

Because of the knowledge of the codons corresponding to the variousamino acids, availability of a protein sequence provides a descriptionof all the polynucleotides capable of encoding the subject. Thedegeneracy of the genetic code, where the same amino acids are encodedby alternative or synonymous codons allows an extremely large number ofnucleic acids to be made, all of which encode the improved transaminaseenzymes disclosed herein. Thus, having identified a particular aminoacid sequence, those skilled in the art could make any number ofdifferent nucleic acids by simply modifying the sequence of one or morecodons in a way which does not change the amino acid sequence of theprotein. In this regard, the present disclosure specificallycontemplates each and every possible variation of polynucleotides thatcould be made by selecting combinations based on the possible codonchoices, and all such variations are to be considered specificallydisclosed for any polypeptide disclosed herein, including the amino acidsequences presented in Table 3 or Table 4.

In various embodiments, the codons are preferably selected to fit thehost cell in which the protein is being produced. For example, preferredcodons used in bacteria are used to express the gene in bacteria;preferred codons used in yeast are used for expression in yeast; andpreferred codons used in mammals are used for expression in mammaliancells.

In certain embodiments, all codons need not be replaced to optimize thecodon usage of the transaminases since the natural sequence willcomprise preferred codons and because use of preferred codons may not berequired for all amino acid residues. Consequently, codon optimizedpolynucleotides encoding the transaminase enzymes may contain preferredcodons at about 40%, 50%, 60%, 70%, 80%, or greater than 90% of codonpositions of the full length coding region.

In some embodiments, the polynucleotide comprises a nucleotide sequenceencoding a transaminase polypeptide with an amino acid sequence that hasat least about 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%,95%, 96%, 97%, 98%, or 99% or more sequence identity to any of thereference engineered transaminase polypeptides described herein.Accordingly, in some embodiments, the polynucleotide encodes an aminoacid sequence that is at least about 80%, 85%, 86%, 87%, 88%, 89%, 90%,91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more identical to SEQ IDNO: 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38,40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74,76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108,110, 112, 114, 116, 118, 120, 122, 124, 126, 128, 130, 132, 134, 136,138, 140, 142, 144, 146, 148, 150, 152, 154, 156, 158, 160, 162, 164,166, 168, 170, 172, 174, 176, 178, 180, 182, 184, 186, 188, 190, 192,194, 196, or 198, where the polypeptide has transaminase activity andone or more of the improved properties described herein.

In some embodiments, the polynucleotide comprises a nucleotide sequenceencoding an engineered transaminase polypeptide with an amino acidsequence that has at least about 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%,92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% or more sequence identity tothe polypeptide comprising an amino acid corresponding to SEQ ID NO: 10,where the polypeptide has transaminase activity and one or more of theimproved properties described herein.

In some embodiments, the polynucleotide comprises a nucleotide sequenceencoding an engineered transaminase polypeptide with an amino acidsequence that has at least about 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%,92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% or more sequence identity tothe polypeptide comprising an amino acid corresponding to SEQ ID NO: 16,where the polypeptide has transaminase activity and one or more of theimproved properties described herein.

In some embodiments, the polynucleotide comprises a nucleotide sequenceencoding an engineered transaminase polypeptide with an amino acidsequence that has at least about 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%,92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% or more sequence identity tothe polypeptide comprising an amino acid corresponding to SEQ ID NO:18,where the polypeptide has transaminase activity and one or more of theimproved properties described herein.

In some embodiments, the polynucleotides encoding the engineeredtransaminases are selected from SEQ ID NO: 3, 5, 7, 9, 11, 13, 15, 17,19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 45, 47, 49, 51, 53,55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 87, 89,91, 93, 95, 97, 99, 101, 103, 105, 107, 109, 111, 113, 115, 117, 119,121, 123, 125, 127, 129, 131, 133, 135, 137, 139, 141, 143, 145, 147,149, 151, 153, 155, 157, 159, 161, 163, 165, 167, 169, 171, 173, 175,177, 179, 181, 183, 185, 187, 189, 191, 193, 195, and 197.

In some embodiments, the polynucleotides are capable of hybridizingunder highly stringent conditions to a polynucleotide corresponding toSEQ ID NO: 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33,35, 37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69,71, 73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 101, 103,105, 107, 109, 111, 113, 115, 117, 119, 121, 123, 125, 127, 129, 131,133, 135, 137, 139, 141, 143, 145, 147, 149, 151, 153, 155, 157, 159,161, 163, 165, 167, 169, 171, 173, 175, 177, 179, 181, 183, 185, 187,189, 191, 193, 195, or 197, or a complement thereof, and encodes apolypeptide having transaminase activity with one or more of theimproved properties described herein.

In some embodiments, the polynucleotides encode the polypeptidesdescribed herein but have about 80% or more sequence identity, about80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%,98%, or 99% or more sequence identity at the nucleotide level to areference polynucleotide encoding the engineered transaminase. In someembodiments, the reference polynucleotide sequence is selected from SEQID NO: 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35,37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71,73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 101, 103, 105,107, 109, 111, 113, 115, 117, 119, 121, 123, 125, 127, 129, 131, 133,135, 137, 139, 141, 143, 145, 147, 149, 151, 153, 155, 157, 159, 161,163, 165, 167, 169, 171, 173, 175, 177, 179, 181, 183, 185, 187, 189,191, 193, 195, and 197.

An isolated polynucleotide encoding an improved transaminase polypeptidemay be manipulated in a variety of ways to provide for expression of thepolypeptide. Manipulation of the isolated polynucleotide prior to itsinsertion into a vector may be desirable or necessary depending on theexpression vector. The techniques for modifying polynucleotides andnucleic acid sequences utilizing recombinant DNA methods are well knownin the art. Guidance is provided in Sambrook et al., 2001, MolecularCloning: A Laboratory Manual, 3^(rd) Ed., Cold Spring Harbor LaboratoryPress; and Current Protocols in Molecular Biology, Ausubel. F. ed.,Greene Pub. Associates, 1998, updates to 2006.

For bacterial host cells, suitable promoters for directing transcriptionof the nucleic acid constructs of the present disclosure, include thepromoters obtained from the E. coli lac operon, Streptomyces coelicoloragarase gene (dagA), Bacillus subtilis levansucrase gene (sacB),Bacillus licheniformis alpha-amylase gene (amyL), Bacillusstearothermophilus maltogenic amylase gene (amyM), Bacillusamyloliquefaciens alpha-amylase gene (amyQ), Bacillus licheniformispenicillinase gene (penP), Bacillus subtilis xylA and xylB genes, andprokaryotic beta-lactamase gene (VIIIa-Kamaroff et al., 1978, Proc.Natl. Acad. Sci. USA 75: 3727-3731), as well as the tac promoter (DeBoeret al., 1983, Proc. Natl. Acad. Sci. USA 80: 21-25).

For filamentous fungal host cells, suitable promoters for directing thetranscription of the nucleic acid constructs of the present disclosureinclude promoters obtained from the genes for Aspergillus oryzae TAKAamylase, Rhizomucor miehei aspartic proteinase, Aspergillus nigerneutral alpha-amylase, Aspergillus niger acid stable alpha-amylase,Aspergillus niger or Aspergillus awamori glucoamylase (glaA), Rhizomucormiehei lipase, Aspergillus oryzae alkaline protease, Aspergillus oryzaetriose phosphate isomerase, Aspergillus nidulans acetamidase, andFusarium oxysporum trypsin-like protease (WO 96/00787), as well as theNA2-tpi promoter (a hybrid of the promoters from the genes forAspergillus niger neutral alpha-amylase and Aspergillus oryzae triosephosphate isomerase), and mutant, truncated, and hybrid promotersthereof.

In a yeast host, useful promoters can be from the genes forSaccharomyces cerevisiae enolase (ENO-1), Saccharomyces cerevisiaegalactokinase (GAL1), Saccharomyces cerevisiae alcoholdehydrogenase/glyceraldehyde-3-phosphate dehydrogenase (ADH2/GAP), andSaccharomyces cerevisiae 3-phosphoglycerate kinase. Other usefulpromoters for yeast host cells are described by Romanos et al., 1992,Yeast 8:423-488.

The control sequence may also be a suitable transcription terminatorsequence, a sequence recognized by a host cell to terminatetranscription. The terminator sequence is operably linked to the 3′terminus of the nucleic acid sequence encoding the polypeptide. Anyterminator which is functional in the host cell of choice may be used inthe present invention.

For example, exemplary transcription terminators for filamentous fungalhost cells can be obtained from the genes for Aspergillus oryzae TAKAamylase, Aspergillus niger glucoamylase, Aspergillus nidulansanthranilate synthase, Aspergillus niger alpha-glucosidase, and Fusariumoxysporum trypsin-like protease.

Exemplary terminators for yeast host cells can be obtained from thegenes for Saccharomyces cerevisiae enolase, Saccharomyces cerevisiaecytochrome C (CYC1), and Saccharomyces cerevisiaeglyceraldehyde-3-phosphate dehydrogenase. Other useful terminators foryeast host cells are described by Romanos et al., 1992, supra.

The control sequence may also be a suitable leader sequence, anontranslated region of an mRNA that is important for translation by thehost cell. The leader sequence is operably linked to the 5′ terminus ofthe nucleic acid sequence encoding the polypeptide. Any leader sequencethat is functional in the host cell of choice may be used. Exemplaryleaders for filamentous fungal host cells are obtained from the genesfor Aspergillus oryzae TAKA amylase and Aspergillus nidulans triosephosphate isomerase. Suitable leaders for yeast host cells are obtainedfrom the genes for Saccharomyces cerevisiae enolase (ENO-1),Saccharomyces cerevisiae 3-phosphoglycerate kinase, Saccharomycescerevisiae alpha-factor, and Saccharomyces cerevisiae alcoholdehydrogenase/glyceraldehyde-3-phosphate dehydrogenase (ADH2/GAP).

The control sequence may also be a polyadenylation sequence, a sequenceoperably linked to the 3′ terminus of the nucleic acid sequence andwhich, when transcribed, is recognized by the host cell as a signal toadd polyadenosine residues to transcribed mRNA. Any polyadenylationsequence which is functional in the host cell of choice may be used inthe present invention. Exemplary polyadenylation sequences forfilamentous fungal host cells can be from the genes for Aspergillusoryzae TAKA amylase, Aspergillus niger glucoamylase, Aspergillusnidulans anthranilate synthase, Fusarium oxysporum trypsin-likeprotease, and Aspergillus niger alpha-glucosidase. Usefulpolyadenylation sequences for yeast host cells are described by Guo andSherman, 1995, Mol Cell Bio 15:5983-5990.

The control sequence may also be a signal peptide coding region thatcodes for an amino acid sequence linked to the amino terminus of apolypeptide and directs the encoded polypeptide into the cell'ssecretory pathway. The 5′ end of the coding sequence of the nucleic acidsequence may inherently contain a signal peptide coding region naturallylinked in translation reading frame with the segment of the codingregion that encodes the secreted polypeptide. Alternatively, the 5′ endof the coding sequence may contain a signal peptide coding region thatis foreign to the coding sequence. The foreign signal peptide codingregion may be required where the coding sequence does not naturallycontain a signal peptide coding region.

Alternatively, the foreign signal peptide coding region may simplyreplace the natural signal peptide coding region in order to enhancesecretion of the polypeptide. However, any signal peptide coding regionwhich directs the expressed polypeptide into the secretory pathway of ahost cell of choice may be used in the present invention.

Effective signal peptide coding regions for bacterial host cells are thesignal peptide coding regions obtained from the genes for Bacillus NClB11837 maltogenic amylase, Bacillus stearothermophilus alpha-amylase,Bacillus licheniformis subtilisin, Bacillus licheniformisbeta-lactamase, Bacillus stearothermophilus neutral proteases (nprT,nprS, nprM), and Bacillus subtilis prsA. Further signal peptides aredescribed by Simonen and Palva, 1993, Microbiol Rev 57: 109-137.

Effective signal peptide coding regions for filamentous fungal hostcells can be the signal peptide coding regions obtained from the genesfor Aspergillus oryzae TAKA amylase, Aspergillus niger neutral amylase,Aspergillus niger glucoamylase, Rhizomucor miehei aspartic proteinase,Humicola insolens cellulase, and Humicola lanuginosa lipase.

Useful signal peptides for yeast host cells can be from the genes forSaccharomyces cerevisiae alpha-factor and Saccharomyces cerevisiaeinvertase. Other useful signal peptide coding regions are described byRomanos et al., 1992, supra.

The control sequence may also be a propeptide coding region that codesfor an amino acid sequence positioned at the amino terminus of apolypeptide. The resultant polypeptide is known as a proenzyme orpropolypeptide (or a zymogen in some cases). A propolypeptide can beconverted to a mature active polypeptide by catalytic or autocatalyticcleavage of the propeptide from the propolypeptide. The propeptidecoding region may be obtained from the genes for Bacillus subtilisalkaline protease (aprE), Bacillus subtilis neutral protease (nprT),Saccharomyces cerevisiae alpha-factor, Rhizomucor miehei asparticproteinase, and Myceliophthora thermophila lactase (WO 95/33836).

Where both signal peptide and propeptide regions are present at theamino terminus of a polypeptide, the propeptide region is positionednext to the amino terminus of a polypeptide and the signal peptideregion is positioned next to the amino terminus of the propeptideregion.

It may also be desirable to add regulatory sequences, which allow theregulation of the expression of the polypeptide relative to the growthof the host cell. Examples of regulatory systems are those which causethe expression of the gene to be turned on or off in response to achemical or physical stimulus, including the presence of a regulatorycompound. In prokaryotic host cells, suitable regulatory sequencesinclude the lac, tac, and trp operator systems. In yeast host cells,suitable regulatory systems include, as examples, the ADH2 system orGAL1 system. In filamentous fungi, suitable regulatory sequences includethe TAKA alpha-amylase promoter, Aspergillus niger glucoamylasepromoter, and Aspergillus oryzae glucoamylase promoter.

Other examples of regulatory sequences are those which allow for geneamplification. In eukaryotic systems, these include the dihydrofolatereductase gene, which is amplified in the presence of methotrexate, andthe metallothionein genes, which are amplified with heavy metals. Inthese cases, the nucleic acid sequence encoding the polypeptide of thepresent invention would be operably linked with the regulatory sequence.

Thus, in another aspect, the present disclosure is also directed to arecombinant expression vector comprising a polynucleotide encoding anengineered transaminase polypeptide or a variant thereof, and one ormore expression regulating regions such as a promoter and a terminator,a replication origin, etc., depending on the type of hosts into whichthey are to be introduced. The various nucleic acid and controlsequences described above may be joined together to produce arecombinant expression vector which may include one or more convenientrestriction sites to allow for insertion or substitution of the nucleicacid sequence encoding the polypeptide at such sites. Alternatively, thenucleic acid sequence of the present disclosure may be expressed byinserting the nucleic acid sequence or a nucleic acid constructcomprising the sequence into an appropriate vector for expression. Increating the expression vector, the coding sequence is located in thevector so that the coding sequence is operably linked with theappropriate control sequences for expression.

The recombinant expression vector may be any vector (e.g., a plasmid orvirus), which can be conveniently subjected to recombinant DNAprocedures and can bring about the expression of the polynucleotidesequence. The choice of the vector will typically depend on thecompatibility of the vector with the host cell into which the vector isto be introduced. The vectors may be linear or closed circular plasmids.

The expression vector may be an autonomously replicating vector, i.e., avector that exists as an extrachromosomal entity, the replication ofwhich is independent of chromosomal replication, e.g., a plasmid, anextrachromosomal element, a minichromosome, or an artificial chromosome.The vector may contain any means for assuring self-replication.Alternatively, the vector may be one which, when introduced into thehost cell, is integrated into the genome and replicated together withthe chromosome(s) into which it has been integrated. Furthermore, asingle vector or plasmid or two or more vectors or plasmids whichtogether contain the total DNA to be introduced into the genome of thehost cell, or a transposon may be used.

The expression vector of the present invention preferably contains oneor more selectable markers, which permit easy selection of transformedcells. A selectable marker is a gene the product of which provides forbiocide or viral resistance, resistance to heavy metals, prototrophy toauxotrophs, and the like. Examples of bacterial selectable markers arethe dal genes from Bacillus subtilis or Bacillus licheniformis, ormarkers, which confer antibiotic resistance such as ampicillin,kanamycin, chloramphenicol (Example 1) or tetracycline resistance.Suitable markers for yeast host cells are ADE2, HIS3, LEU2, LYS2, MET3,TRP1, and URA3.

Selectable markers for use in a filamentous fungal host cell include,but are not limited to, amdS (acetamidase), argB (ornithinecarbamoyltransferase), bar (phosphinothricin acetyltransferase), hph(hygromycin phosphotransferase), niaD (nitrate reductase), pyrG(orotidine-5′-phosphate decarboxylase), sC (sulfate adenyltransferase),and trpC (anthranilate synthase), as well as equivalents thereof.Embodiments for use in an Aspergillus cell include the amdS and pyrGgenes of Aspergillus nidulans or Aspergillus oryzae and the bar gene ofStreptomyces hygroscopicus.

The expression vectors of the present invention can contain anelement(s) that permits integration of the vector into the host cell'sgenome or autonomous replication of the vector in the cell independentof the genome. For integration into the host cell genome, the vector mayrely on the nucleic acid sequence encoding the polypeptide or any otherelement of the vector for integration of the vector into the genome byhomologous or nonhomologous recombination.

Alternatively, the expression vector may contain additional nucleic acidsequences for directing integration by homologous recombination into thegenome of the host cell. The additional nucleic acid sequences enablethe vector to be integrated into the host cell genome at a preciselocation(s) in the chromosome(s). To increase the likelihood ofintegration at a precise location, the integrational elements shouldpreferably contain a sufficient number of nucleic acids, such as 100 to10,000 base pairs, preferably 400 to 10,000 base pairs, and mostpreferably 800 to 10,000 base pairs, which are highly homologous withthe corresponding target sequence to enhance the probability ofhomologous recombination. The integrational elements may be any sequencethat is homologous with the target sequence in the genome of the hostcell. Furthermore, the integrational elements may be non-encoding orencoding nucleic acid sequences. On the other hand, the vector may beintegrated into the genome of the host cell by non-homologousrecombination.

For autonomous replication, the vector may further comprise an origin ofreplication enabling the vector to replicate autonomously in the hostcell in question. Examples of bacterial origins of replication are P15Aon (as shown in the plasmid of FIG. 5) or the origins of replication ofplasmids pBR322, pUC19, pACYC177 (which plasmid has the P15A ori), orpACYC184 permitting replication in E. coli, and pUB110, pE194, pTA1060,or pAM 1 permitting replication in Bacillus. Examples of origins ofreplication for use in a yeast host cell are the 2 micron origin ofreplication, ARS1, ARS4, the combination of ARS1 and CEN3, and thecombination of ARS4 and CEN6. The origin of replication may be onehaving a mutation which makes its functioning temperature-sensitive inthe host cell (see, e.g., Ehrlich, 1978, Proc Natl Acad. Sci. USA75:1433).

More than one copy of a nucleic acid sequence of the present inventionmay be inserted into the host cell to increase production of the geneproduct. An increase in the copy number of the nucleic acid sequence canbe obtained by integrating at least one additional copy of the sequenceinto the host cell genome or by including an amplifiable selectablemarker gene with the nucleic acid sequence where cells containingamplified copies of the selectable marker gene, and thereby additionalcopies of the nucleic acid sequence, can be selected for by cultivatingthe cells in the presence of the appropriate selectable agent.

Many of the expression vectors for use in the present invention arecommercially available. Suitable commercial expression vectors includep3xFLAGTM™ expression vectors from Sigma-Aldrich Chemicals, St. LouisMo., which includes a CMV promoter and hGH polyadenylation site forexpression in mammalian host cells and a pBR322 origin of replicationand ampicillin resistance markers for amplification in E. coli. Othersuitable expression vectors are pBluescriptll SK(−) and pBK-CMV, whichare commercially available from Stratagene, LaJolla Calif., and plasmidswhich are derived from pBR322 (Gibco BRL), pUC (Gibco BRL), pREP4, pCEP4(Invitrogen) or pPoly (Lathe et al., 1987, Gene 57:193-201).

6.5 Host Cells for Expression of Transaminase Polypeptides

In another aspect, the present disclosure provides a host cellcomprising a polynucleotide encoding an improved transaminasepolypeptide of the present disclosure, the polynucleotide beingoperatively linked to one or more control sequences for expression ofthe transaminase enzyme in the host cell. Host cells for use inexpressing the polypeptides encoded by the expression vectors of thepresent invention are well known in the art and include but are notlimited to, bacterial cells, such as E. coli, Vibrio fluvialis,Streptomyces and Salmonella typhimurium cells; fungal cells, such asyeast cells (e.g., Saccharomyces cerevisiae or Pichia pastoris (ATCCAccession No. 201178)); insect cells such as Drosophila S2 andSpodoptera Sf9 cells; animal cells such as CHO, COS, BHK, 293, and Bowesmelanoma cells; and plant cells. Appropriate culture mediums and growthconditions for the above-described host cells are well known in the art.

Polynucleotides for expression of the transaminase may be introducedinto cells by various methods known in the art. Techniques include amongothers, electroporation, biolistic particle bombardment, liposomemediated transfection, calcium chloride transfection, and protoplastfusion. Various methods for introducing polynucleotides into cells willbe apparent to the skilled artisan.

An exemplary host cell is Escherichia coli W3110. The expression vectorwas created by operatively linking a polynucleotide encoding an improvedtransaminase into the plasmid pCK110900 operatively linked to the lacpromoter under control of the lad repressor. The expression vector alsocontained the P15a origin of replication and the chloramphenicolresistance gene.

6.6 Methods of Generating Engineered Transaminase Polypeptides

In some embodiments, to make the improved polynucleotides andpolypeptides of the present disclosure, the naturally-occurringtransaminase enzyme that catalyzes the transamination reaction isobtained (or derived) from Vibrio fluvialis. In some embodiments, theparent polynucleotide sequence is codon optimized to enhance expressionof the transaminase in a specified host cell. As an illustration, theparental polynucleotide sequence encoding the wild-type polypeptide ofVibrio fluvialis was constructed from oligonucleotides prepared basedupon the known polypeptide sequence of Vibrio fluvialis sequence (Shinet al., 2003, “Purification, characterization, and molecular cloning ofa novel amine:pyruvate transaminase from Vibrio fluvialis JS17” ApplMicrobiol Biotechnol. 61(5-6):463-471). The parental polynucleotidesequence, designated as SEQ ID NO: 1, was codon optimized for expressionin E. coli and the codon-optimized polynucleotide cloned into anexpression vector, placing the expression of the transaminase gene underthe control of the lac promoter and lad repressor gene. Clonesexpressing the active transaminase in E. coli were identified and thegenes sequenced to confirm their identity. The sequence designated SEQID NO: 17 was the parent sequence utilized as the starting point formost experiments and library construction of engineered transaminasesevolved from the Vibrio fluvialis transaminase.

The engineered transaminases can be obtained by subjecting thepolynucleotide encoding the naturally occurring transaminase tomutagenesis and/or directed evolution methods, as discussed above. Anexemplary directed evolution technique is mutagenesis and/or DNAshuffling as described in Stemmer, 1994, Proc Natl Acad Sci USA91:10747-10751; WO 95/22625; WO 97/0078; WO 97/35966; WO 98/27230; WO00/42651; WO 01/75767 and U.S. Pat. No. 6,537,746. Other directedevolution procedures that can be used include, among others, staggeredextension process (StEP), in vitro recombination (Zhao et al., 1998,Nat. Biotechnol. 16:258-261), mutagenic PCR (Caldwell et al., 1994, PCRMethods Appl. 3:S136-S140), and cassette mutagenesis (Black et al.,1996, Proc Natl Acad Sci USA 93:3525-3529). Mutagenesis and directedevolution techniques useful for the purposes herein are also describedin the following references: Ling, et al., 1997, Anal. Biochem.254(2):157-78; Dale et al., 1996, “Oligonucleotide-directed randommutagenesis using the phosphorothioate method,” In Methods Mol. Biol.57:369-74; Smith, 1985, Ann. Rev. Genet. 19:423-462; Botstein et al.,1985, Science 229:1193-1201; Carter, 1986, Biochem. J. 237:1-7; Krameret al., 1984, Cell, 38:879-887; Wells et al., 1985, Gene 34:315-323;Minshull et al., 1999, Curr Opin Chem Biol 3:284-290; Christians et al.,1999, Nature Biotech 17:259-264; Crameri et al., 1998, Nature391:288-291; Crameri et al., 1997, Nature Biotech 15:436-438; Zhang etal., 1997, Proc Natl Acad Sci USA 94:45-4-4509; Crameri et al., 1996,Nature Biotech 14:315-319; Stemmer, 1994, Nature 370:389-391; Stemmer,1994, Proc Natl Acad Sci USA 91:10747-10751; WO 95/22625; WO 97/0078; WO97/35966; WO 98/27230; WO 00/42651; WO 01/75767 and U.S. Pat. No.6,537,746. All publications are incorporated herein by reference.

The clones obtained following mutagenesis treatment can be screened forengineered transaminases having a desired improved enzyme property.Measuring enzyme activity from the expression libraries can be performedusing the standard biochemistry techniques, such as HPLC analysisfollowing OPA derivitization of the product amine.

Where the improved enzyme property desired is thermostability, enzymeactivity may be measured after subjecting the enzyme preparations to adefined temperature and measuring the amount of enzyme activityremaining after heat treatments. Clones containing a polynucleotideencoding a transaminase are then isolated, sequenced to identify thenucleotide sequence changes (if any), and used to express the enzyme ina host cell.

Where the sequence of the engineered polypeptide is known, thepolynucleotides encoding the enzyme can be prepared by standardsolid-phase methods, according to known synthetic methods. In someembodiments, fragments of up to about 100 bases can be individuallysynthesized, then joined (e.g., by enzymatic or chemical litigationmethods, or polymerase mediated methods) to form any desired continuoussequence. For example, polynucleotides and oligonucleotides of theinvention can be prepared by chemical synthesis using, e.g., theclassical phosphoramidite method described by Beaucage et al., 1981, TetLett 22:1859-69, or the method described by Matthes et al., 1984, EMBOJ. 3:801-05, e.g., as it is typically practiced in automated syntheticmethods. According to the phosphoramidite method, oligonucleotides aresynthesized, e.g., in an automatic DNA synthesizer, purified, annealed,ligated and cloned in appropriate vectors. In addition, essentially anynucleic acid can be obtained from any of a variety of commercialsources.

Engineered transaminase enzymes expressed in a host cell can berecovered from the cells and or the culture medium using any one or moreof the well known techniques for protein purification, including, amongothers, lysozyme treatment, sonication, filtration, salting-out,ultra-centrifugation, and chromatography. Suitable solutions for lysingand the high efficiency extraction of proteins from bacteria, such as E.coli, are commercially available under the trade name CelLytic B™ fromSigma-Aldrich of St. Louis Mo.

Chromatographic techniques for isolation of the transaminase polypeptideinclude, among others, reverse phase chromatography high performanceliquid chromatography, ion exchange chromatography, gel electrophoresis,and affinity chromatography. Conditions for purifying a particularenzyme will depend, in part, on factors such as net charge,hydrophobicity, hydrophilicity, molecular weight, molecular shape, etc.,and will be apparent to those having skill in the art.

In some embodiments, affinity techniques may be used to isolate theimproved transaminase enzymes. For affinity chromatography purification,any antibody which specifically binds the transaminase polypeptide maybe used. For the production of antibodies, various host animals,including but not limited to rabbits, mice, rats, etc., may be immunizedby injection with a transaminase polypeptide, or a fragment thereof. Thetransaminase polypeptide or fragment may be attached to a suitablecarrier, such as BSA, by means of a side chain functional group orlinkers attached to a side chain functional group. Various adjuvants maybe used to increase the immunological response, depending on the hostspecies, including but not limited to Freund's (complete andincomplete), mineral gels such as aluminum hydroxide, surface activesubstances such as lysolecithin, pluronic polyols, polyanions, peptides,oil emulsions, keyhole limpet hemocyanin, dinitrophenol, and potentiallyuseful human adjuvants such as BCG (bacilli Calmette Guerin) andCorynebacterium parvum.

6.7 Methods of Using the Engineered Transaminase Enzymes and CompoundsPrepared Therewith

In some embodiments, the transaminases described herein can be used in amethod for performing processes shown in Schemes 1 to 3, supra, in whichan amino group from an amino donor of general Formula II is transferredto an amino acceptor (ketone substrate) of general Formula I to producea chiral amine. The reaction can produce the R chiral amine or S chiralamine in stereomeric excess. Generally, the method for performing thetransamination reaction can comprise contacting or incubating the aminodonor of Formula II and an amino acceptor of Formula I,

with an engineered transaminase polypeptide of the disclosure underreaction conditions suitable for converting the amine acceptor to the(S) or (R) chiral amine in stereomeric excess. Suitable groups for R¹,R², R³ and R⁴ are described above.

In some embodiments of the method, the amino acceptors can be selectedfrom pyruvate, dihydronaphthalen-1(2H)-one, 1-phenylbutan-2-one,3,3-dimethylbutan-2-one, octan-2-one, ethyl 3-oxobutanoate,4-phenylbutan-2-one, 1-(4-bromophenyl)ethanone, and2-methyl-cyclohexanone and 7-methoxy-2-tetralone,1-(6-methoxynaphthalen-2-yl)ethanone,1-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)ethanone,1-(4-phenoxyphenyl)ethanone, (R)-4-oxotetrahydro-2H-pyran-3-yl-benzoate,and (R)-3-(benzyloxy)dihydro-2H-pyran-4(3H)-one.

Accordingly, in some embodiments, the method comprises contactingdihydronaphthalen-1(2H)-one with a transaminase polypeptide of thedisclosure in presence of an amino donor under suitable reactionconditions for the conversion of dihydronaphthalen-1(2H)-one to(S)-1,2,3,4-tetrahydronaphthalen-1-amine in enantiomeric excess. In someembodiments of the process, the product(S)-1,2,3,4-tetrahydronaphthalen-1-amine can be formed in at least 10%20% 30% 40% 50% 60%, 70%, 80%, 90%, or 95% or more stereomeric excess.

In some embodiments, the method comprises contacting 1-phenylbutan-2-onewith a transaminase polypeptide of the disclosure in presence of anamino donor under suitable reaction conditions for the conversion of1-phenylbutan-2-one to (S)-1-phenylbutan-2-amine in enantiomeric excess.In some embodiments of the process, the product(S)-1-phenylbutan-2-amine can be formed in at least 10% 20% 30% 40% 50%60%, 70%, 80%, 90%, or 95% or more stereomeric excess.

In some embodiments, in some embodiments, the method comprisescontacting 3,3-dimethylbutan-2-one with a transaminase polypeptide ofthe disclosure in presence of an amino donor under suitable reactionconditions for the conversion of 3,3-dimethylbutan-2-one to(S)-3,3-dimethylbutan-2-amine in enantiomeric excess. In someembodiments of the process, the product (S)-3,3-dimethylbutan-2-aminecan be formed in at least 10% 20% 30% 40% 50% 60%, 70%, 80%, 90%, or 95%or more stereomeric excess.

In some embodiments, the method comprises contacting octan-2-one with atransaminase polypeptide of the disclosure in presence of an amino donorunder suitable reaction conditions for the conversion of octan-2-one to(S)-octan-2-amine in enantiomeric excess. In some embodiments of theprocess, the product (S)-octan-2-amine can be formed in at least 10%20%30% 40% 50% 60%, 70%, 80%, 90%, or 95% or more stereomeric excess.

In some embodiments, the method comprises contacting1-(4-bromophenyl)ethanone with a transaminase polypeptide of thedisclosure in presence of an amino donor under suitable reactionconditions for the conversion of 1-(4-bromophenyl)ethanone to(S)-1-(4-bromophenyl)ethanamine in enantiomeric excess. In someembodiments of the process, the product (S)-1-(4-bromophenyl)ethanaminecan be formed in at least 10% 20% 30% 40% 50% 60%, 70%, 80%, 90%, or 95%or more stereomeric excess.

In some embodiments, the method comprises contacting 4-phenylbutan-2-onewith a transaminase polypeptide of the disclosure in presence of anamino donor under suitable reaction conditions for the conversion of4-phenylbutan-2-one to (R)-4-phenylbutan-2-amine in enantiomeric excess.In some embodiments of the process, the product(R)-4-phenylbutan-2-amine can be formed in at least 10% 20% 30% 40% 50%60%, 70%, 80%, 90%, or 95° A or more stereomeric excess.

In some embodiments, the method comprises contacting ethyl3-oxobutanoate with a transaminase polypeptide of the disclosure inpresence of an amino donor under suitable reaction conditions for theconversion of ethyl 3-oxobutanoate to (R)-ethyl 3-aminobutanoate inenantiomeric excess. In some embodiments of the process, the product(R)-ethyl 3-aminobutanoate can be formed in at least 10% 20% 30% 40% 50%60%, 70%, 80%, 90%, or 95% or more stereomeric excess.

In some embodiments, the method comprises contacting ethyl3-oxobutanoate with a transaminase polypeptide of the disclosure inpresence of an amino donor under suitable reaction conditions for theconversion of ethyl 3-oxobutanoate to (S)-ethyl 3-aminobutanoate inenantiomeric excess. In some embodiments of the process, the product(S)-ethyl 3-aminobutanoate can be formed in at least 10%20% 30% 40% 50%60%, 70%, 80%, 90%, or 95% or more stereomeric excess.

In some embodiments, the method comprises contacting1-(6-methoxynaphthalen-2-yl)ethanone with a transaminase polypeptide ofthe disclosure in presence of an amino donor under suitable reactionconditions for the conversion of 1-(6-methoxynaphthalen-2-yl)ethanone to(S)-1-(6-methoxynaphthalen-2-yl)ethanamine in stereomeric excess.

In some embodiments, the method comprises contacting1-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)ethanone with a transaminasepolypeptide of the disclosure in presence of an amino donor undersuitable reaction conditions for the conversion of1-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)ethanone to(S)-1-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)ethanamine in stereomericexcess.

In some embodiments, the method comprises contacting1-(4-phenoxyphenyl)ethanone with a transaminase polypeptide of thedisclosure in presence of an amino donor under suitable reactionconditions for the conversion of 1-(4-phenoxyphenyl)ethanone to(S)-1-(4-phenoxyphenyl)ethanamine in stereomeric excess.

In some embodiments, the method comprises contacting(R)-3-(benzyloxy)dihydro-2H-pyran-4(3H)-one with a transaminasepolypeptide of the disclosure in presence of an amino donor undersuitable reaction conditions for the conversion of(R)-3-(benzyloxy)dihydro-2H-pyran-4(3H)-one, to(3S,4S)-3-(benzyloxy)tetrahydro-2H-pyran-4-amine in stereomeric excess.

In some embodiments of the method, the amino donor comprises a compoundof Formula II, as described herein. In some embodiments of the method,the amino donor is selected from isopropylamine (2-amino propane),α-phenethylamine, D-alanine, L-alanine, or D,L-alanine, particularlyisopropylamine.

In the methods, any of the engineered transaminase described herein canbe used to convert the amine acceptor in presence of an amino donor toproduce the chiral amine. In some embodiments, the engineeredtransaminases used in the method comprises an amino acid sequence thatis at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%or more identical to the sequence of SEQ ID NO: 10, 16, or 18. Theseengineered transaminases can have one or more of improved properties,including among others, thermostability, solvent stability,isopropylamine resistance, increased enzymatic activity,stereoselectivity, and/or substrate recognition/binding.

In some embodiments of the method, the engineered transaminases can haveone or more residue differences as compared to the naturally occurringtransaminase of SEQ ID NO:2 or an a reference engineered transaminase,such as SEQ ID NO:18, at the following residue positions: X4, X9, X12,X21, X30, X31, X44, X45, X, 56, X57, X81, X82, X85, X86, X95, X112,X113, X127, X147, X153, X157, X166, X177, X181, X208, X211, X228, X233,X253, X272, X294, X297, X302, X311, X314, X316, X317, X318, X319, X320,X321, X324, X385, X391, X398, X407, X408, X409, X415, X417, X418, X420,X431, X434, X438, X444, and X446.

Guidance in choosing an engineered transaminase for a specific amineacceptor substrate is provided in the descriptions herein, such as inTable 3 and Table 4, which shows the activities of various engineeredtransaminases for structurally different amino acceptor substrates. Insome embodiments of the method, the engineered transaminase can comprisean amino acid sequence corresponding to SEQ ID NO: 4, 6, 8, 10, 16, 18,20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54,56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88. 90,92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116, 118, 120,122, 124, 126, 128, 130, 132, 134, 136, 138, 140, 142, 144, 146, 148,150, 152, 154, 156, 158, 160, 162, 164, 166, 168, 170. 172, 174, 176,178, 180, 182, 184, 186, 188, 190, 192, 194, 196, or 198.

In some embodiments of the method for enantiomeric enrichment of achiral amine, additional quantities of the amino acceptor can be added(up to saturation) and/or the amino acceptor (ketone) formed can becontinuously removed from the reaction mixture. Conversely, when theundesired chiral form of the amine is converted to the amino acceptor(ketone) byproduct and the desired chiral form is not, the latter can bereadily isolated by conventional techniques. A partial separation can beeffected by acidification, extraction with a hydrocarbon such as heptaneto remove the ketone, rendering the aqueous phase basic, andre-extraction with a hydrocarbon such as heptane. When, on the otherhand, both chiral forms of the amine are desired, the form which isconverted to the ketone can be removed from the reaction mixture (orfrom the aqueous phase in a two phase mixture) and independentlysubjected to the action of an omega-transaminase in the presence of anamino donor to generate the same chiral form which was initiallyconverted to the ketone.

As noted herein, the transaminases of the disclosure can be used tomediate the reverse reaction in Scheme 1, i.e., the conversion of thechiral amine of Formula III to the ketone of Formula I along withconversion of the ketone of Formula IV to the amine of Formula II.Stereospecific conversion of either the (R) or (S) chiral amine can beused for the chiral resolution of mixtures of (R) and (S) amines.Accordingly, in some embodiments, the process for chiral resolution cancomprise contacting a mixture of (R) and (S) chiral amine of formula Ma(e.g., a racemic mixture) with a stereospecific transaminase of thedisclosure in presence of ketone of Formula IV,

under suitable reaction conditions for formation of the ketone ofFormula I and the amine of Formula II, thereby generating a mixturehaving a stereomeric excess of the chiral amine of Formula IIIb.

As is known by those of skill in the art, transamination reactionstypically require a cofactor. Reactions catalyzed by the engineeredtransaminase enzymes described herein also typically require a cofactor,although many embodiments of the engineered transaminases require farless cofactor than reactions catalyzed with wild-type transaminaseenzymes. As used herein, the term “cofactor” refers to a non-proteincompound that operates in combination with a transaminase enzyme.Cofactors suitable for use with the engineered transaminase enzymesdescribed herein include, but are not limited to, pyridoxal-5′-phosphate(also known as pyridoxal-phosphate, PLP, P5P). In some embodiments, thePLP cofactor is provided in the cell extract and does not need to beadded. In some embodiments utilizing highly purified transaminaseenzyme, the cofactor is added to the reaction mixture either at thebeginning of the reaction or additional cofactor may be added during thereaction. In some embodiments, a different member of the vitamin B₆family, such as pyridoxine, is used in place of PLP.

In some embodiments, the transaminase reactions can be carried inpresence of reduced cofactor, nicotinamide adenine dinucleotide (NADH),which can limit the inactivation of the transaminase enzyme (see vanOphem et al., 1998, Biochemistry 37(9):2879-88). In some embodiments, acofactor regeneration system, such as glucose dehydrogenase (GDH) andglucose or formate dehydrogease and formate can be used to regenerateNADH in the reaction medium.

The transamination reactions described herein are generally carried outin a solvent. Suitable solvents include water, organic solvents (e.g.,ethanol, dimethyl sulfoxide (DMSO), ethyl acetate, butyl acetate,1-octanol, heptane, octane, methyl t-butyl ether (MTBE), toluene, andthe like), ionic liquids (e.g., 1-ethyl 4-methylimidazoliumtetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate,1-butyl-3-methylimidazolium hexafluorophosphate, and the like). In someembodiments, aqueous solvents, including water and aqueous co-solventsystems, are used.

Exemplary aqueous co-solvent systems comprises water and one or moreorganic solvent. In general, an organic solvent component of an aqueousco-solvent system is selected such that it does not completelyinactivate the transaminase enzyme. Appropriate co-solvent systems canbe readily identified by measuring the enzymatic activity of thespecified engineered transaminase enzyme with a defined substrate ofinterest in the candidate solvent system, utilizing an enzyme activityassay, such as those described herein.

The organic solvent component of an aqueous co-solvent system may bemiscible with the aqueous component, providing a single liquid phase, ormay be partly miscible or immiscible with the aqueous component,providing two liquid phases. Generally, when an aqueous co-solventsystem is employed, it is selected to be biphasic, with water dispersedin an organic solvent, or vice-versa. Generally, when an aqueousco-solvent system is utilized, it is desirable to select an organicsolvent that can be readily separated from the aqueous phase. Ingeneral, the ratio of water to organic solvent in the co-solvent systemis typically in the range of from about 1% to about 99% (v/v) organicsolvent to water. The co-solvent system may be pre-formed prior toaddition to the reaction mixture, or it may be formed in situ in thereaction vessel.

The aqueous solvent (water or aqueous co-solvent system) may bepH-buffered or unbuffered. Generally, the transaminase reaction can becarried out at a pH of about 10 or below, usually in the range of fromabout 5 to about 10. In some embodiments, the transaminase reaction iscarried out at a pH of about 9 or below, usually in the range of fromabout 5 to about 9. In some embodiments, the transaminase reaction iscarried out at a pH of about 8 or below, often in the range of fromabout 5 to about 8, and usually in the range of from about 6 to about 8.The transaminase reaction may also be carried out at a pH of about 7.8or below, or 7.5 or below. Alternatively, the transaminase reaction maybe carried out a neutral pH, i.e., about 7.

During the course of the transamination reactions, the pH of thereaction mixture may change. The pH of the reaction mixture may bemaintained at a desired pH or within a desired pH range by the additionof an acid or a base during the course of the reaction. Alternatively,the pH may be controlled by using an aqueous solvent that comprises abuffer. Suitable buffers to maintain desired pH ranges are known in theart and include, for example, phosphate buffer, triethanolamine buffer,and the like. Combinations of buffering and acid or base addition mayalso be used.

In carrying out the transamination reactions described herein, theengineered transaminase enzyme may be added to the reaction mixture inthe form of the purified enzymes, whole cells transformed with gene(s)encoding the enzymes, and/or cell extracts and/or lysates of such cells.The gene(s) encoding the engineered transaminase enzymes can betransformed into host cells separately or together into the same hostcell. For example, in some embodiments one set of host cells can betransformed with gene(s) encoding one engineered transaminase enzyme andanother set can be transformed with gene(s) encoding another engineeredtransaminase. Both sets of transformed cells can be utilized together inthe reaction mixture in the form of whole cells, or in the form oflysates or extracts derived therefrom. In other embodiments, a host cellcan be transformed with gene(s) encoding multiple engineeredtransaminase enzymes. In some embodiments the engineered polypeptidescan be expressed in the form of secreted polypeptides and the culturemedium containing the secreted polypeptides can be used for thetransaminase reaction.

Whole cells transformed with gene(s) encoding the engineeredtransaminase enzyme or cell extracts, lysates thereof, and isolatedenzymes may be employed in a variety of different forms, including solid(e.g., lyophilized, spray-dried, and the like) or semisolid (e.g., acrude paste).

The cell extracts or cell lysates may be partially purified byprecipitation (ammonium sulfate, polyethyleneimine, heat treatment orthe like, followed by a desalting procedure prior to lyophilization(e.g., ultrafiltration, dialysis, and the like). Any of the cellpreparations may be stabilized by crosslinking using known crosslinkingagents, such as, for example, glutaraldehyde or immobilization to asolid phase (e.g., Eupergit C, and the like).

The solid reactants (e.g., enzyme, salts, etc.) may be provided to thereaction in a variety of different forms, including powder (e.g.,lyophilized, spray dried, and the like), solution, emulsion, suspension,and the like. The reactants can be readily lyophilized or spray driedusing methods and equipment that are known to those having ordinaryskill in the art. For example, the protein solution can be frozen at−80° C. in small aliquots, then added to a prechilled lyophilizationchamber, followed by the application of a vacuum.

The quantities of reactants used in the transamination reaction willgenerally vary depending on the quantities of product desired, andconcomitantly the amount of transaminase substrate employed. Thosehaving ordinary skill in the art will readily understand how to varythese quantities to tailor them to the desired level of productivity andscale of production. In general, the transaminase substrates are kept atlevels that achieve essentially complete or near complete conversion ofthe substrates into products.

The order of addition of reactants is not critical. The reactants may beadded together at the same time to a solvent (e.g., monophasic solvent,biphasic aqueous co-solvent system, and the like), or alternatively,some of the reactants may be added separately, and some together atdifferent time points. For example, the cofactor, transaminase, andtransaminase substrate may be added first to the solvent.

For improved mixing efficiency when an aqueous co-solvent system isused, the transaminase, and cofactor may be added and mixed into theaqueous phase first. The organic phase may then be added and mixed in,followed by addition of the transaminase substrate. Alternatively, thetransaminase substrate may be premixed in the organic phase, prior toaddition to the aqueous phase

Suitable conditions for carrying out the transaminase-catalyzedtransamination reactions described herein include a wide variety ofconditions which can be readily optimized by routine experimentationthat includes, but is not limited to, contacting the engineeredtransaminase enzyme and substrate at an experimental pH and temperatureand detecting product, for example, using the methods described in theExamples provided herein.

The transaminase catalyzed reaction is typically carried out at atemperature in the range of from about 15° C. to about 60° C. For someembodiments, the reaction is carried out at a temperature in the rangeof from about 20° C. to about 55° C. For some embodiments, the reactionis carried out at a temperature in the range of from about 35° C. toabout 50° C. In still other embodiments, it is carried out at atemperature in the range of from about 40° C. to about 50° C. Thereaction may also be carried out under ambient conditions.

The transamination reaction is generally allowed to proceed untilessentially complete, or near complete, transformation of substrate isobtained. Transformation of substrate to product can be monitored usingknown methods by detecting substrate and/or product. Suitable methodsinclude gas chromatography, HPLC, and the like. Conversion yields of thechiral amine product generated in the reaction mixture are generallygreater than about 50%, may also be greater than about 60%, may also begreater than about 70%, may also be greater than about 80%, may also begreater than 90%, and are often greater than about 97%.

7. EXAMPLES

Various features and embodiments of the disclosure are illustrated inthe following representative examples, which are intended to beillustrative, and not limiting.

Example 1 Screen for Thermostable Transaminase Variants UsingIsopropylamine as Amine-Donor

The following method was used to screen transaminase libraries for athermostable backbone from which most polypeptide variants were evolved.Biotransformations were performed in 96-well plates and contained thefollowing: 1.0 M isopropylamine (pH 7.5) and 1.0 M pyruvate in 100 mMtriethanolamine hydrochloride buffer (pH 7.5). The amine product(alanine) was then converted to its corresponding isoindole productusing o-phthaldialdehyde/N-acetylcysteine reagent (OPA), separated byHPLC, and quantified using external standards.

Reagents, per well:

Component Volume/Well Final conc. Pyruvate, pH 7.5 (2.5M) 80 μL 1.0M IPM(5.0M, pH 7.5) 40 μL 1.0M 1.0M TEA, pH 7.5 20 μL 100 mM Water 20 μLLysate 40 μL 200 μL/well final volume.

Biotransformations.

Lysate containing transaminase variants was added to 96-well roundbottom plates (40 μL/well). The plates were heat-sealed and incubated at50° C. for 24 h. After 24 h at 50° C., reactions were initiated byaddition of a 160 mL/well of a 50° C. pre-heated solution of 1.25 Mpyruvate, 1.25 M isopropylamine, and 125 mM triethanolamine (pH 7.5).The reactions were briefly agitated, heat sealed, and returned to the50° C. incubator. After 2 h, 10 mL/well biotransformation wastransferred to a 96-well plate containing 190 mL/well aqueous 0.5 mMhydroxylamine. This hydroxylamine-quenched plate was heat-sealed andstored in a 4° C. refrigerator for later analysis. The reaction platewas heat-sealed and returned to the 50° C. incubator. After 24 h totalreaction time, another 10 mL/well aliquot of biotransformation was addedto a new 96-well plate containing 190 mL/well 0.5 mM hydroxylamine. Thequenched biotransformations (both the 2 h and the 24 h timepoints) werethen OPA derivatized and analyzed by HPLC. Quantification of alanine wasperformed as follows:

-   -   1. 20 μL/well quenched biotransformation was transferred to an        empty 96-well plate.    -   2. Six standards containing mixtures of known amounts of        isopropylamine and alanine (50 mM total amine concentration)        were prepared and 20 μL of each standard was added to a second        96-well plate.    -   3. Both the quenched biotransformation plate and the standards        plate were transferred to an HPLC equipped with an autosampler.    -   4. On-line OPA derivatization of each sample to the        corresponding isoindole product was performed immediately prior        to HPLC analysis by automated addition of 80 μL OPA        derivatization reagent to each 20 μL aliquot.    -   5. The isoindole products were separated by HPLC and detected by        absorbance at 320 nm.    -   6. Peak areas of the standards were used to generate a        calibration curve.    -   7. Alanine product concentrations were calculated from the        calibration curve and accounted for dilution steps.

Example 2 Generation of Highly Expressed Vibrio fluvialis TransaminaseVariants

A gene encoding the wild-type omega transaminase from Vibrio fluvialisSEQ ID NO:1 based on the reported amino acid sequence (Kim and/or Shin)was synthesized and cloned into an in-house pCK110900 vector system(United States Patent Application Publication 20060195947) andsubsequently expressed in E. coli W3110fhuA. Two random mutagenesislibraries were generated, with individual colonies grown in 96-wellplates. Crude lysate from the cells was then used to screen forincreased activity. Screening conditions were as follows: 1.0 Misopropylamine and 110 mM pyruvate in 100 mM triethanolamine buffer (pH9) at 50° C. for 4-4.5 h. Reactions were quenched by addition of 0.5 mMaqueous hydroxylamine hydrochloride and then analyzed by HPLC. Variantsthat produced significantly higher yields of the product (L-alanine)were sequenced and analyzed by SDS-PAGE, revealing that N-terminalmutations, both coding and non-coding (up to and including the 12^(th)residue), are capable of greatly increasing expression levels.

TABLE 5 Amino Acid Expression Nuc ID Sequence Changes Silent mutationsLevel 193 E12K; E302K g309t +++++ 3 c18t; c286t +++++ 5 A9T c852t; g861a+++ 7 P4R g891c +++++ 11 A9T; F86Y; M294V; c852t; g861a +++++ 13 g12a;g15a; c18t +++++ 195 S6R; A133T; Y184F; P252Q; t561c +++ I314F 197 S6I+++++ +++: 1-5x increase over wt ++++: 5-10x increase over wt +++++:10-20x increase over wt

Example 3 Amination of Ethyl 3-Oxobutanoate Using Isopropylamine asAmine-Donor

The following example describes the conditions for performing thefollowing reaction:

A high-throughput method was used to screen transaminase libraries forpolypeptide variants using isopropylamine as the amine-donor.Biotransformations were performed in 96-well plates and contained thefollowing: 50 mM isopropylamine (pH 7.0) and 50 mM ethyl 3-oxobutanoatein 100 mM triethanolamine hydrochloride buffer (pH 7.0) containing 5%ethanol Amine products were converted to their corresponding isoindoleproducts using o-phthaldialdehyde/N-acetylcysteine reagent (OPA),separated by HPLC, and quantified using external standards.

Biotransformations were initiated by addition of 70 μL lysate containing100 μM PLP to 30 μL “reaction mixture.” Reaction mixture consisted of167 mM isopropylamine (pH 7.0) and 167 mM ethyl 3-oxobutanoate in 333 mMtriethanolamine buffer (pH 7.0) containing 16.7% ethanol.Biotransformations were agitated at room temperature for 17 h and thenquenched by addition of 0.1 volume of 1.5 mM aqueous hydroxylaminehydrochloride.

Quantification of ethyl 3-aminobutanoate was performed as follows:

-   -   1. 20 μL/well quenched biotransformation was transferred to an        empty 96-well plate.    -   2. Six standards containing mixtures of known amounts of        isopropylamine and ethyl 3-aminobutanoate (50 mM total amine        concentration) were prepared and 20 μL of each standard was        added to a second 96-well plate.    -   3. Both the quenched biotransformation plate and the standards        plate were transferred to an HPLC equipped with an autosampler.    -   4. On-line OPA derivatization of each sample to the        corresponding isoindole product was performed immediately prior        to HPLC analysis by automated addition of 80 μL OPA        derivatization reagent to each 20 μL aliquot.    -   5. The isoindole products were separated by HPLC and detected by        absorbance at 320 nm.    -   6. Peak areas of the standards were used to generate a        calibration curve.    -   7. ethyl 3-aminobutanoate product concentrations were calculated        from the calibration curve and accounted for dilution steps.

The procedure in this example was also used to screen transaminaselibraries with 3,4-dihydronaphthalen-1(2M-one, 1-phenylbutan-2-one,2-methylcyclohexanone, and 1-(4-bromophenyl)ethanone as the aminoacceptor.

Example 4 Amination of Octan-2-One Using Isopropylamine as Amine-Donor

The following example describes the conditions for performing thefollowing reaction:

The following high-throughput method was used to screen transaminaselibraries for variants using isopropylamine as the amine-donor.Biotransformations were performed in 96-well plates and contained thefollowing: 200 mM isopropylamine (pH 7.0) and 100 mM octan-2-one in 100mM triethanolamine hydrochloride buffer (pH 7.0) containing 5% ethanolAmine products were converted to their corresponding isoindole productsusing o-phthaldialdehyde/N-acetylcysteine reagent (OPA), separated byHPLC, and quantified using external standards.

Biotransformations were initiated by addition of 80 μL lysate containing100 μM PLP to 20 μL “reaction mixture.” Reaction mixture consisted of1.0 M isopropylamine (pH 7.0) and 500 mM octan-2-one in 500 mMtriethanolamine buffer (pH 7.0) containing 25% ethanol.Biotransformations were agitated at room temperature for 17 h and thenquenched by addition of 3 volumes of 0.5 mM aqueous hydroxylaminehydrochloride.

Quantification of octan-2-amine was performed as follows:

-   -   1. 20 μL/well quenched biotransformation was transferred to an        empty 96-well plate.    -   2. Six standards containing mixtures of known amounts of        isopropylamine and octan-2-amine (50 mM total amine        concentration) were prepared and 20 μL of each standard was        added to a second 96-well plate.    -   3. Both the quenched biotransformation plate and the standards        plate were transferred to an HPLC equipped with an autosampler.    -   4. On-line OPA derivatization of each sample to the        corresponding isoindole product was performed immediately prior        to HPLC analysis by automated addition of 80 μL OPA        derivatization reagent to each 20 μL aliquot.    -   5. The isoindole products were separated by HPLC and detected by        absorbance at 320 nm.    -   6. Peak areas of the standards were used to generate a        calibration curve.    -   7. Octan-2-amine product concentrations were calculated from the        calibration curve and accounted for dilution steps.

Example 5 Amination of 3,3-Dimethylbutan-2-One Using Isopropylamine asAmine-Donor

The following example describes the conditions for performing thefollowing reaction,

The following high-throughput method was used to screen transaminaselibraries for polypeptide variants using isopropylamine as theamine-donor. Biotransformations were performed in 96-well plates andcontained the following: 200 mM isopropylamine (pH 7.0) and 100 mM3,3-dimethylbutan-2-one in 100 mM triethanolamine hydrochloride buffer(pH 7.0) containing 5% ethanol Amine products were converted to theircorresponding isoindole products usingo-phthaldialdehyde/N-acetylcysteine reagent (OPA), separated by HPLC,and quantified using external standards.

Biotransformations were initiated by addition of 40 μL lysate containing100 μM PLP to 60 μL “reaction mixture.” Reaction mixture consisted of333 mM isopropylamine (pH 7.0) and 167 mM 3,3-dimethylbutan-2-one in 167mM triethanolamine buffer (pH 7.0) containing 8.3% ethanol.Biotransformations were agitated at room temperature for 17 h and thenquenched by addition of 3 volumes of 0.5 mM aqueous hydroxylaminehydrochloride.

Quantification of 3,3-dimethylbutan-2-amine was performed as follows:

-   -   1. 20 μL/well quenched biotransformation was transferred to an        empty 96-well plate.    -   2. Six standards containing mixtures of known amounts of        isopropylamine and 3,3-dimethylbutan-2-amine (50 mM total amine        concentration) were prepared and 20 μL of each standard was        added to a second 96-well plate.    -   3. Both the quenched biotransformation plate and the standards        plate were transferred to an HPLC equipped with an autosampler.    -   4. On-line OPA derivatization of each sample to the        corresponding isoindole product was performed immediately prior        to HPLC analysis by automated addition of 80 μL OPA        derivatization reagent to each 20 μL aliquot.    -   5. The isoindole products were separated by HPLC and detected by        absorbance at 320 nm.    -   6. Peak areas of the standards were used to generate a        calibration curve.    -   7. 3,3-dimethylbutan-2-amine product concentrations were        calculated from the calibration curve and accounted for dilution        steps.

The procedure in this example was also used to screen transaminaselibraries with 4-phenylbutan-2-one as the amino acceptor.

Example 6 Amination of 1-(6-Methoxynapthalene-2-yl)Ethanone to itsCorresponding S-Amine

Reaction Conditions and Analysis:

Transaminase variants were assayed for conversion of the ketonesubstrate 1-(6-methoxynapthalene-2-yl)ethanone to its correspondingamine product (S)-1-(6-methoxynapthalene-2-yl)ethanamine according tothe following reaction conditions: 1 mg/mL (or 6.25 mg/mL) ketonesubstrate, 0.5 mg/mL PLP, 0.5 mg/mL NAD, 0.1 mg/mL lactate dehydrogenase(LDH), 1 mg/mL formate dehydrogenase (FDH), 90 mg/mL L-alanine, 40 mg/mLformate, 5 vol % DMSO, buffer pH 7.5. The reaction mixture was allowedto react for 24 h with shaking at 30° C. Alternatively, GDH and glucosecan replace FDH and formate for recycling NAD co-factor. Typicalconcentrations are as follows: 1 mg/mL GDH, 90 mg/mL glucose.

Additionally, a subset of variants were screened under the sameconditions except using isopropylamine (iPr-NH₂) rather than L-alanineas the amine donor for the reaction. according to the followingconditions: 1 mg/mL (or 5 mg/mL) ketone substrate, 0.5 mg/mL PLP, 1 MiPr-NH₂, 5-40 vol % DMSO in 100 mM triethanolamine buffer, pH 7.5 or8.5. The reaction mixture was allowed to react for 24 h at 30° C.

Following the reaction, the mixture is extracted into an organic solventphase (e.g., ethyl acetate, propyl acetate or methyl t-butyl ether) andanalyzed by HPLC. Percent conversion is calculated based on peak areasas the ratio of amine product peak area to (ketone substrate peakarea+amine product peak area).

As shown by the results listed in Table 6, reactions using alanine asamine donor resulted in substantially higher conversion than reactionsusing isopropylamine as donor. Reactions with alanine as donor and 1.0mg/mL substrate loading were able to convert up to 21.3% of thesubstrate-(6-methoxynapthalene-2-yl)ethanone to its corresponding amineproduct.

At least the following residue differences are associated with theability to convert at least 2.0% substrate to its corresponding amineproduct: W57A/C/F/I/L/S, Y86A/F/G/H/S, V153A/C/Q/S, P233L/T, F317L,P318F/G/R, G320A, F321L, L417A/S/T/V, and F438L.

TABLE 6 1.0 mg/mL 6.25 mg/mL SEQ Residue differences iPr- substratesubstrate ID (as compared to NH₂ (alanine (alanine NO: SEQ ID NO: 18)donor donor) donor) 126 W57L; Y86F; V153S; P233T; +++ +++++ ++++ L417T154 W57C; Y86S; L417T +++ +++++ ++++ 134 W57S; P233L; L417V +++++ ++++140 W57A; V153S; P318G ++ +++++ +++++ 148 W57A; V153C; F321L +++++ ++++178 W57L; Y86S; V153A ++ +++++ +++ 136 W57S; Y86G; L417C +++++ ++++ 180W57L; Y86F; P318F ++ +++++ ++++ 146 W57F; Y86F; V153Q ++ ++++ ++++ 144W57I; Y86F; G320A + ++++ +++ 166 W57C; Y86A; F317L ++++ +++ 114 W57L;L417C; F438L ++ +++ +++ 150 Y86F; P318R; L417A +++ +++ 142 W57F; Y86H;V153Q +++ +++ 174 W57F; P318F; L417S +++ ++ 110 Y86H; V153S; C181R; +++++ ++ L417T 172 V153S; F317L; L417C + +++ ++ 190 V153T; A228G; L417A+++ ++ 116 W57F; M127L; L417C +++ ++ 138 A228G; F317L; L417C +++ ++ 184P233L; F321L; L417I +++ 152 A228G; P318G; L417C +++ ++ 28 W57L ++ ++++++ 86 L417C + +++ + 92 Y86H; V153S; L417C ++ +++ + 162 Y86H; P233L;L417A +++ ++ 48 Y86S; V153S ++ + 156 Y86F; V153C; V297A ++ ++ ++ 182V153S; A228G; L417V ++ 192 W57F; P318G; L417I ++ 78 L417A ++ + 26 Y86F++ 84 L417I ++ 170 V153T; A228G; F321L ++ 186 F317L; P318R; L417T ++ 188V153C; F317Y; H319Q ++ 24 Y86N + 46 W57I; V153S + + + 88 Y86H; V153A;L417C + 102 V153A; P233T; L417C + 108 M95T; V153A; L417C + 168 Y86N;A228G; F317L + 158 Y86S; V153T; V297A + + ≧0.2% ++ ≧0.5% +++ ≧1.0% ++++≧5.0% +++++ ≧10.0%

Example 7 Transaminase Variants Capable of Converting Ketone Substrate1-(2,3-Dihydrobenzo[b][1.4]Dioxin-6-yl)Ethanone to its CorrespondingS-Amine Product

Reaction Conditions and Analysis:

Transaminase variants were assayed for conversion of the ketonesubstrate 1-(2,3-dihydrobenzo[b][1.4]dioxin-6-yl)ethanone to itscorresponding amine product(S)-1-(2,3-dihydrobenzo[b][1.4]dioxin-6-yl)ethanamine according to thefollowing reaction conditions: 1 mg/mL ketone substrate, 0.5 mg/mL PLP,0.5 mg/mL NAD, 0.1 mg/mL LDH, 1 mg/mL FDH, 90 mg/mL L-alanine, 40 mg/mLformate, 5 vol % DMSO, buffer pH 7.5. The reaction mixture was allowedto react for 24 h at 30° C.

Following the reaction, the mixture is extracted into an organic solventphase (e.g., ethyl acetate, propyl acetate or methyl t-butyl ether) andanalyzed by HPLC. Percent conversion is calculated based on peak areasas the ratio of amine product peak area to (ketone substrate peakarea+amine product peak area).

As shown by the results listed in Table 7, variants were able to convertup to 9.3% of ketone substrate1-(2,3-dihydrobenzo[b][1.4]dioxin-6-yl)ethanone to its correspondingS-amine product. The positive control fluvialis TA of SEQ ID NO:18exhibited only 0.7% conversion.

At least the following residue differences are associated with theability to convert at least 2.0% substrate of formula (2) to itscorresponding amine product: W57A/C/F/I/L/S, Y86F/G/S, V153A/C/Q/S,A228G, P233L/T, V297A, P318F/G, G320A, L417C/T/V, and F438L.

TABLE 7 SEQ ID Residue Differences Conv. NO: (as compared to SEQ ID NO:18) (%) 152 W57C; Y86S; L417T +++ 146 W57F; Y86F; V153Q +++ 126 W57L;Y86F; V153S; P233T; L417T +++ 156 Y86F; V153C; V297A ++ 28 W57L ++ 114W57L; L417C; F438L ++ 134 W57S; P233L; L417V ++ 178 W57L; Y86S; V153A ++136 W57S; Y86G; L417C ++ 140 W57A; V153S; P318G ++ 42 W57I ++ 46 W57I;V153S ++ 144 W57I; Y86F; G320A ++ 180 W57L; Y86F; P318F ++ 182 V153S;A228G; L417V ++ 26 Y86F ++ 166 W57C; Y86A; F317L + 104 V153S; P233S +148 W57A; V153C; F321L + 72 V153G + 48 Y86S; V153S + 84 L417I + 110Y86H; V153S; C181R; L417T + 16 D21N; H45N; L177V; T208I; K211R; G324S;A391T + 44 V153S + 98 V31A + 106 Y86H; V153A; A228G; L417I + 164 V153C;P233L; P318R + + ≧0.8% ++ ≧2.0% +++ ≧5.0%

Example 8 Transaminase Variants Capable of Converting Ketone Substrate1-(4-Phenoxyphenyl)Ethanone to its Corresponding S-Amine Product

Reaction conditions and analysis for conversion of ketone substrate:Transaminase variants were assayed for conversion of the ketonesubstrate 1-(4-phenoxyphenyl)ethanone to its corresponding amine product(S)-1-(4-phenoxyphenyl)ethanamine according to the following reactionconditions: 1 mg/mL ketone substrate, 0.5 mg/mL PLP, 0.5 mg/mL NAD, 0.1mg/mL LDH, 1 mg/mL FDH, 90 mg/mL L-alanine, 40 mg/mL formate, 5 vol %DMSO, buffer pH 7.5. The reaction mixture was allowed to react for 24 hat 30° C.

Following the reaction, the mixture is extracted into an organic solventphase (e.g., ethyl acetate, propyl acetate or methyl t-butyl ether) andanalyzed by HPLC. Percent conversion is calculated based on peak areasas the ratio of amine product peak area to (ketone substrate peakarea+amine product peak area).

As shown by the results listed in Table 8, variants were able to convertup to 2.0% of ketone substrate 1-(4-phenoxyphenyl)ethanone to itscorresponding S-amine product. The positive control fluvialis TA of SEQID NO:18 exhibited no detectable conversion under the assay conditions.

At least the following residue differences are associated with theability to convert at least 0.5% substrate of formula (3) to itscorresponding amine product: W57C/F/I/L, Y86H/F/S, V153A/C/Q/S, C181R,P233T, V297A, P318F, L417C/T, and F438L.

TABLE 8 SEQ ID Residue Differences Conv. NO: (as compared to SEQ ID NO:18) (%) 16 D21N; H45N; L177V; T208I; K211R; G324S; A391T + 20 Y86S + 26Y86F + 28 W57L ++ 42 W57I + 44 V153S + 46 W57I; V153S + 48 Y86S; V153S +72 V153G + 78 L417A + 84 L417I + 88 Y86H; V153A; L417C + 90 Y86H;V153A + 92 Y86H; V153S; L417C + 98 V31A + 104 V153S; P233S + 106 Y86H;V153A; A228G; L417I + 108 M95T; V153A; L417C + 110 Y86H; V153S; C181R;L417T + 114 W57L; L417C; F438L + 126 W57L; Y86F; V153S; P233T; L417T ++134 W57S; P233L; L417V + 136 W57S; Y86G; L417C + 140 W57A; V153S;P318G + 142 W57F; Y86H; V153Q + 144 W57I; Y86F; G320A + 146 W57F; Y86F;V153Q ++ 154 W57C; Y86S; L417T ++ 156 Y86F; V153C; V297A ++ 162 Y86H;P233L; L417A + 164 V153C; P233L; P318R + 166 W57C; Y86A; F317L + 178W57L; Y86S; V153A ++ 180 W57L; Y86F; P318F + 182 V153S; A228G; L417V +190 V153T; A228G; L417A + + ≧0.2% ++ ≧1.0%

Example 9 Transaminase Variants Capable of Converting Ketone Substrate(R)-4-Oxotetrahydro-2H-Pyran-3-yl Benzoate to its Corresponding S-AmineProduct

Reaction Conditions and Analysis:

Transaminase variants were assayed for conversion of the ketonesubstrate (R)-4-oxotetrahydro-2H-pyran-3-yl benzoate to itscorresponding amine product (3S,4S)-4-aminotetrahydro-2H-pyran-3-ylbenzoate according to the following reaction conditions: 1 mg/mL ketonesubstrate, 0.5 mg/mL PLP, 0.5 mg/mL NAD, 0.1 mg/mL LDH, 1 mg/mL FDH, 90mg/mL L-alanine, 40 mg/mL formate, 5 vol % DMSO, buffer pH 7.5. Thereaction mixture was allowed to react for 24 h at 30° C.

Following the reaction, the mixture is extracted into an organic solventphase (e.g., ethyl acetate, propyl acetate or methyl t-butyl ether) andanalyzed by HPLC. Percent conversion is calculated based on peak areasas the ratio of amine product peak area to (ketone substrate peakarea+amine product peak area).

As shown by the results listed in Table 9, variants were able to convertup to 57% of ketone substrate (R)-4-oxotetrahydro-2H-pyran-3-yl benzoateto its corresponding S-amine product. The positive control fluvialis TAof SEQ ID NO:18 exhibited no detectable conversion.

At least the following residue differences are associated with theability to convert at least 1% substrate(R)-4-oxotetrahydro-2H-pyran-3-yl benzoate to its corresponding S-amineproduct: W57A/C/I/L/S, Y86A/F/G/S, V153C/S, P233T, F317L, P318G, G320A,F321L, and L417T.

TABLE 9 SEQ ID Residue Differences NO: (as compared to SEQ ID NO: 18) %Conversion 140 W57A; V153S; P318G +++ 148 W57A; V153C; F321L +++ 178W57L; Y86S; V153A ++ 144 W57I; Y86F; G320A ++ 136 W57S; Y86G; L417C ++126 W57L; Y86F; V153S; P233T; L417T ++ 154 W57C; Y86S; L417T ++ 166W57C; Y86A; F317L ++ 46 W57I; V153S + + ≧1% ++ ≧5% +++ ≧50%

Example 10 Transaminase Variants Capable of Converting Ketone Substrate(R)-3-(Benzyloxy)Dihydro-2H-Pyran-4(3H)-One to its Corresponding S-AmineProduct

Reaction Conditions and Analysis:

Transaminase variants were assayed for conversion of the ketonesubstrate (R)-3-(benzyloxy)dihydro-2H-pyran-4(3H)-one to itscorresponding amine product(3S,4S)-3-(benzyloxy)tetrahydro-2H-pyran-4-amine according to thefollowing reaction conditions: 1 mg/mL ketone substrate, 0.5 mg/mL PLP,0.5 mg/mL NAD, 0.1 mg/mL LDH, 1 mg/mL FDH, 90 mg/mL L-alanine, 40 mg/mLformate, 5 vol % DMSO, buffer pH 7.5. The reaction mixture was allowedto react for 24 h at 30° C.

Following the reaction, the mixture is extracted into an organic solventphase (e.g., ethyl acetate, propyl acetate or methyl t-butyl ether) andanalyzed by HPLC. Percent conversion is calculated based on peak areasas the ratio of amine product peak area to (ketone substrate peakarea+amine product peak area).

As shown by the results listed in Table 10, variants were able toconvert up to 100% of ketone substrate(R)-3-(benzyloxy)dihydro-2H-pyran-4(3H)-one to its corresponding amineproduct. The positive control fluvialis TA of SEQ ID NO:18 exhibitedonly 9% conversion.

At least the following residue differences are associated with theability to convert at least 90% substrate(R)-3-(benzyloxy)dihydro-2H-pyran-4(3H)-one to its corresponding S-amineproduct: W57F/I/S; G81D; F85S; Y86F/G/H/N; M127L; V153C/Q/S; A228G;V297A; F317L; P318F/R; L417A/C/V; and F438L.

TABLE 10 SEQ ID Residue Differences NO: (as compared to SEQ ID NO: 18) %Conversion 42 W57I ++++ 46 W57I; V153S ++++ 92 Y86H; V153S; L417C ++++116 W57F; M127L; L417C ++++ 126 W57L; Y86F; V153S; P233T; L417T ++++ 134W57S; P233L; L417V ++++ 136 W57S; Y86G; L417C ++++ 140 W57A; V153S;P318G ++++ 148 W57A; V153C; F321L ++++ 154 W57C; Y86S; L417T ++++ 166W57C; Y86A; F317L ++++ 178 W57L; Y86S; V153A ++++ 180 W57L; Y86F; P318F++++ 28 W57L ++++ 144 W57I; Y86F; G320A ++++ 114 W57L; L417C; F438L ++++22 G81D; Y86H ++++ 146 W57F; Y86F; V153Q +++ 192 W57F; P318G; L417I +++110 Y86H; V153S; C181R; L417T +++ 106 Y86H; V153A; A228G; L417I +++ 156Y86F; V153C; V297A +++ 172 V153S; F317L; L417C +++ 174 W57F; P318F;L417S +++ 142 W57F; Y86H; V153Q +++ 190 V153T; A228G; L417A +++ 186F317L; P318R; L417T +++ 90 Y86H; V153A +++ 176 V153T; H319V; L417I +++182 V153S; A228G; L417V +++ 48 Y86S; V153S +++ 108 M95T; V153A; L417C+++ 88 Y86H; V153A; L417C +++ 128 F85S; V153A; P233T +++ 150 Y86F;P318R; L417A +++ 98 V31A +++ 130 W57I; F85A; Y86H; L417C +++ 138 A228G;F317L; L417C +++ 36 F85S; V153A +++ 26 Y86F +++ 158 Y86S; V153T; V297A+++ 162 Y86H; P233L; L417A ++ 102 V153A; P233T; L417C ++ 122 F85A;W147G; V153A ++ 40 F85A; V153A ++ 86 L417C ++ 100 I314V; D409G ++ 132F85A; V153S; L417S ++ 170 V153T; A228G; F321L ++ 50 P318G; T408A ++ 184P233L; F321L; L417I ++ 52 Y82H ++ 78 L417A ++ 188 V153C; F317Y; H319Q ++94 T30A ++ 164 V153C; P233L; P318R ++ 34 V153A; F317L; P318G ++ 96 V44A;N166S ++ 152 A228G; P318G; L417C ++ 44 V153S ++ 72 V153G ++ 104 V153S;P233S ++ 84 L417I ++ 70 V153N ++ 68 V153T + 160 V153S; P318R; L417E +168 Y86N; A228G; F317L + 60 F85T + 20 Y86S + 118 I311V; I314T + 30 Y82H;L417F + 32 F85A; F317L + 58 F85S + 82 G320A + 62 F85A + 80 H319Q + 74F317M + 76 F317Y + 112 Y113C; K385R; L417C + 38 Y113H; C407S + 54 E12G;M434V + 120 F112I; F317L + + ≧10% ++ ≧20% +++ ≧50% ++++ ≧90%

All publications, patents, patent applications and other documents citedin this application are hereby incorporated by reference in theirentireties for all purposes to the same extent as if each individualpublication, patent, patent application or other document wereindividually indicated to be incorporated by reference for all purposes.

While various specific embodiments have been illustrated and described,it will be appreciated that various changes can be made withoutdeparting from the spirit and scope of the invention(s).

1-91. (canceled)
 92. An engineered transaminase enzyme comprising apolypeptide comprising an amino acid sequence that is at least 90%identical to SEQ ID NO:2 and has an amino acid residue substitutions ascompared to SEQ ID NO:2 at one or more residue positions selected fromthe group consisting of X57, X85, X86, X153, X228, X233, X297, X317,X318, and X417, wherein the polypeptide has transaminase activity. 93.The engineered transaminase enzyme of claim 92, wherein the one or moreamino acid residue substitutions at positions X57, X85, X86, X153, X228,X233, X297, X317, X318, or X417 are selected from the group consistingof: X57 is, A, C, F, I, L, or S; X85 is A, C, S, N, T, G, or V; X86 isF, S, N, A, G, or H; X153 is A, C, G, N, M, Q, S, or T; X228 is G or T;X233 is L, S, I, V, N, G, or T; V297 is A, S, T, I, M, Q, C, or G; X317is L, M, or Y; X318 is G, F, C, K, W, or R; and X417 is A, C, E, F, I,N, Q, Y, S, T, or V.
 94. The engineered transaminase enzyme of claim 92,wherein the amino acid sequence additionally comprises at least onecombination of substitutions selected from the group consisting of: X57is F, X86 is H and X153 is Q; X57 is F, X86 is F and X153 is Q; X57 isL, X86 is S and X153 is A; X57 is L, X86 is F, X153 is S, X233 is T, andX417 is T; X57 is C, X86 is A and X317 is L; X57 is L, X86 is F and X318is F; X57 is C, X86 is S and X417 is T; X57 is S, X86 is G and X417 isC; X57 is A, X153 is S and X318 is G; X57 is S, X233 is L and X417 is V;X57 is F, X318 is F and X417 is S; X57 is F, X318 is G and X417 is I;X85 is S, X153 is A and X233 is T; X85 is A, X153 is S and X417 is S;X86 is H, X153 is A, X228 is G, and X417 is I; X86 is H, X153 is A andX417 is C; X86 is H, X153 is S and X417 is C; X86 is N, X228 is G andX317 is L; X86 is H, X233 μL and X417 is A; X86 is F, X318 is R and X417is A; X153 is A, X233 is T and X417 is C; X153 is C, X233 is L and X318is R; X153 is S, X228 is G and X417 is V; X153 is T, X228 is G and X417is A; X153 is A, X317 is L and X318 is G; X153 is 5, X317 is L and X417is C; X153 is 5, X318 is R and X417 is E; X228 is G, X317 is L and X417is C; X228 is G, X318 is G and X417 is C; and X317 is L, X318 is R andX417 is T.
 95. The engineered transaminase enzyme of claim 92, whereinthe polypeptide further has increased transaminase activity as comparedto SEQ ID NO:2 for conversion of an amino acceptor substrate to thecorresponding chiral amino product.
 96. The engineered transaminaseenzyme of claim 92, wherein the polypeptide further has at least 10%residual activity in the conversion of pyruvate to L-alanine in thepresence of amino donor isopropylamine after treatment of thepolypeptide at 50° C. for 23 h.
 97. A method for the conversion of asubstrate of Formula I to a chiral amine product of Formula III instereomeric excess, the method comprising contacting the substrate ofFormula I with the engineered transaminase enzyme of claim 92 in thepresence of an amino donor under suitable reaction conditions for theconversion of the substrate of Formula I to the chiral amine product ofFormula III

wherein the chiral carbon atom of the chiral amine product is markedwith an *; each of R¹, and R², when taken independently, is anunsubstituted or substituted alkyl, alkylaryl, or aryl group, wherein R¹is different from R² in structure or chirality, or R¹ and R², takentogether, is a hydrocarbon chain of 4 or more carbon atoms containing acenter of chirality.
 98. The method of claim 97, wherein the amino donoris isopropylamine.
 99. The method of claim 97, wherein the suitablereaction conditions comprise a temperature of about 20° C. to about 55°C.
 100. The method of claim 97, wherein the suitable reaction conditionscomprise a temperature of about 35° C. to about 50° C.
 101. Apolynucleotide encoding the engineered transaminase of claim
 92. 102. Anexpression vector comprising the polynucleotide of claim
 101. 103. Ahost cell comprising the polynucleotide of claim
 101. 104. The host ofclaim 103, wherein the host cell is E. coli.